
Book_ 



BURE 



EERING. 



Main Classification...EJSL.^.R.Q.--C^.d..SL.CA.^^C _£____. 
Sub-Classification JtAJLJStA 

(Date when Classified and Indexed ) 



EXPLANATORY— Or Guide for Library Clerk. 

The "Book No." serves as an identification number; and not as a classification or 
a location number. [This number is given to each individual volume, making it sepa- 
rate and distinct, and said number is recorded in a regular "Accession Book."] 

"Main classification" corresponds to section or alcove; and "Sub-classification" 
to a subdivision of section or shelf. 

The "Book No." should be written in with ink, and the remaining lines should 
be filled in with pencil. The number never changes; the classification may, in certain 
cases, be changed. 



GAS AND FUEL ANALYSIS 
FOR ENGINEERS. 



A COMPEND FOR THOSE INTERESTED IN THE 
ECONOMICAL APPLICATION OF FUEL. 



PREPARED ESPECIALLY FOR THE USE OF STUDENTS 

at the 
MASSACHUSETTS INSTITUTE OF TECHNOLOGY. 



:., 



AUGUSTUS H. GILL, S.B., Ph.D., 

Assistant Professor of Gas Analysis at the 

Massachusetts Institute of Technology, Boston, Mass, 

Author of a Short Handbook of Oil Analysis. 



FIRST EDITION. 

FIRST THOUSAND. 



NEW YORK: 

JOHN WILEY & SONS. 

London CHAPMAN & HALL Limited. 

1897. 



-tf 



3^ 1 



Copyright, 1896, 

BY 

AUGUSTUS H. GILL. 



By transfer 

OCT 25 1915 



/* - W 






ROBERT DRUMMOND, ELECTROTYPEK AND PRINTER, NEW YORK. 



PREFACE. 



This little book is an attempt to present in a con- 
cise yet clear form the methods of gas and fuel analy- 
sis involved in testing the efficiency of a boiler plant. 
Its substance was given originally, in the form of 
lectures and heliotyped notes, to the students in the 
courses of Chemical, Mechanical, and Electrical En- 
gineering, but in response to requests it has been 
deemed expedient to give it a wider circulation. 

At the time of its conception, nothing of the kind 
was known to exist in the English language ; in 
German we now have the excellent little book of Dr. 
Ferdinand Fischer, " Taschenbuch fur Feuerungs- 
Techniker." 

The present book is the result of six years' experi- 
ence in the instruction of classes of about one hun- 
dred students. It is in no sense a copy of any other 
work, nor is it a mere compilation. The author has 
in every case endeavored to give credit where any- 
thing has been taken from outside sources ; it is, how- 



m 



IV PREFACE. 

\ 

ever, difficult to credit single ideas, and if he has 
been remiss in this respect it has been unintentional. 

The study of flue-gas analysis enables the engineer 
to investigate the various sources of loss ; and if this 
compend stimulates and renders easy such investiga- 
tion, the writer's purpose will have been accomplished. 
The necessary apparatus can be obtained from the 
leading dealers in New York City. 

The author wishes to acknowledge his indebtedness 
to our former Professor of Analytical Chemistry, Dr. 
Thomas M. Drown, and to Mrs. Ellen H. Richards, 
by whose efforts the department of Gas Analysis was 
established. 

He will also be grateful for any suggestions or cor- 
rections from the profession. 

Massachusetts Institute of Technology, 
Boston, November^ 1896. 



CONTENTS. 



CHAPTER I. PAGE 

Introduction. Sampling — Sampling-tubes. Suction Appa- 
ratus. Gas-holders i 

CHAPTER II. 

Apparatus for the Analysis of Chimney-gases. Apparatus 

of Orsat, Bunte, and Elliott II 

CHAPTER III. 

The Measurement of Temperature- Thermometers — Le 

Chatelier Pyrometer — Metals and Salts 24 

CHAPTER iV. 

Calculations. " Pounds of Air per Pound of Coal," and 
Percentage of Heat Carried off by the Flue-gases. Loss 
due to Formation of Carbonic Oxide. Loss due to Un- 
consumed Fuel 27 

CHAPTER V. 

Preparation of Reagents and Arrangement of the Labo- 
ratory 34 

CHAPTER VI. 

Fuels, Solid, Liquid and Gaseous: their Derivation and 
Composition 40 

CHAPTER VII. 

Fuels. Methods of Analysis and Determination of the 
Heating Value. Determination of the Various Constit- 
uents. The Mahler Bomb and Junker Gas-calorimeter 50 

APPENDIX. 

Tables 79 

v 



LIST OF ILLUSTRATIONS. 



FIG. PAGE 

1. Gas Sampling-tube 3 

2. Sampling Apparatus 4 

3. Sampling Apparatus for Mine-gases 5 

4. Gas-tube 5 

5. Richards's Jet-pump 8 

6. Bunsen's Pump 8 

7. Steam Air-pump 9 

8. Orsat Gas Apparatus 12 

9. Bunte Gas Apparatus 17 

10. Elliott Gas Apparatus 21 

11. Melting-point Boxes 26 

12. Muencke's Aspirator 38 

13. Combustion-furnace 51 

14. Mahler Bomb 58 

15. Mahler Bomb and Calorimeter 59 

16. Junker Gas-calorimeter, section 70 

17. Junker Gas-calorimeter . . , . 71 

vii 



GAS AND FUEL ANALYSIS 



CHAPTER I. 
INTRODUCTION AND METHODS OF SAMPLING. 

UNTIL within recent years, the mechanical engineer 
in testing a boiler plant has been compelled to con- 
tent himself with the bare statement of its efficiency, 
little or no idea being obtained as to the apportion- 
ment of the losses. Knowing the composition and 
temperature of the chimney-gases and the analysis of 
the coal and ash, the loss due to the formation of car- 
bonic oxide, to the imperfect combustion of the coal, 
to the high temperature of the escaping gases, can 
each be determined and thus a basis for their reduc- 
tion to a minimum established. 

By the simple analysis of the chimney-gases and 
determination of their temperature, a very good idea 
of the efficiency of the plant can be obtained previous 
to making the engineering test. For example, in a 
test which the author made in connection with his 
students, the efficiency was increased from 58 to 70 
per cent, upon the results of the gas analysis alone. 



2 GAS AND FUEL ANALYSIS, 

To this end a representative sample must be collected 
according to the method about to be described. 

SAMPLING. 

Before proceeding to take a sample of the gas, the 
plant — for example, a boiler setting — from which the 
gas is to be taken should be thoroughly inspected, 
and all apertures by which the air can enter, carefully 
stopped up. A suitable tube is then inserted air-tight 
in the gas-duct, connected with the sampling or gas 
apparatus, and suction applied, thus drawing the gas 
out. Cork, putty, plaster of Paris, wet cotton-waste, 
or asbestos may be used to render the joint gas-tight. 
The place of insertion should be chosen where the, gas 
will be most completely mixed and least contaminated 
with air. The oil-bath containing the thermometer is 
similarly inserted near the gas-tube, and the tempera- 
ture read from time to time. 

I. Tubes. — The tubes usually employed are Bohe- 
mian-glass combustion tubing or water-cooled metal 
tubes; those of porcelain or platinum are also some- 
times used. Glass and porcelain tubes when subjected 
to high temperatures must be previously warmed or 
gradually inserted: the former may be used up to 
temperatures of 6oo° C. (1200 F.). Uncooled metal 
tubes, other than those of platinum, should under no 
circumstances be used.* 

* Fischer, " Technologie der Brennstoffe," 1SS0, p. 221, states 
that the composition of a gaseous mixture was changed from 1.5 
to 26.0 per cent carbon dioxide, by the passage through an iron 
tube heated to a dull red heat, the carbonic oxide originally 
present reducing the iron oxide with the formation of carbon 
dioxide. 



INTRODUCTION AND METHODS OF SAMPLING. 3 

The metal tube with the water cooling is made as 
shown in Fig. I, c being a piece of brass pipe 3 
feet long, \\ inches outside diameter, b the same 
length, \ inch in diameter, and a \ inch in diameter. 
The water enters at d and leaves at e. The walls of 




Fig. 1. — Gas-sampling Tube. 

the tubes are T V inch thick. The joint at A should 
be brazed; the others may be soldered. 

Platinum tubes from their high cost and small bore 
are seldom used ; they are attacked by carbon, cyan- 
ogen, arsenic, and metallic vapors. 

2. Apparatus for the Collection of Samples.— 
A convenient sampling apparatus is shown in Fig. 2. 
It may be made from a liter separatory funnel — in- 
stead of the bulb there shown — fitted with a rubber 
stopper carrying a tube passing to the bottom and a 
T tube; both of these, except where sulphur-con- 
taining gases are present, can advantageously be 
made of T 3 ¥ -inch lead pipe. The stopper should not 
be fastened down with wire between the tubes after 
the manner of wiring effervescent drinks, as this 
draws the rubber away from the tubes and occasions 
a leak. The fastening shown consists of a brass plate 
fitting upon the top of the stopper, provided with 
screws and nuts which pass through a wire around 



GAS AND FUEL ANALYSIS. 



the neck of the separatory. A chain fastened to the 
plate serves as a convenient method of handling it. 

In using the apparatus, the bulb is filled with water 
by connecting the stem with the water-supply and 
opening one of the pinchcocks upon the T tube; the 




Fig. 2.— Sampling Apparatus. 

water thus entering from the bottom forces the air 
out before it. One branch of the T is connected with 
the sampling-tube and the other with the suction- 
pump, the stopcocks being open, and a current of gas 
drawn down into the pump; upon opening the cock 
upon the stem, the water runs out, drawing a small 
portion of the gas-current passing through the T after 
it into the bulb. It is then taken to a convenient 



INTRODUCTION AND METHODS OF SAMPLING. 5 

place for analysis, the tube h connected with a head of 
water, a branch of the T z, with the gas apparatus, and 
a sample of gas forced over into the ktter for analysis. 




Fig. 4. — Gas-tube. Fig. 3. — Sampling Apparatus for 

Mine-gases. 

Enough water should be left in the bulb to seal the 
stopcock on the bottom and prevent leakage. This 
apparatus is better adapted for the needs of the class- 



6 GAS AND FUEL ANALYSIS. 

room than for actual practice, as it enables the same 
sample to be given to eight or ten students. As has 
been shown by several years' experience, the water 
exercises no appreciable solvent action upon the 
gaseous mixture in the time — about half an hour — 
necessary to collect and distribute the samples. It is 
often necessary to attach about a yard of J-inch 
rubber tubing to the stem of the bulb to prevent air 
being sucked up through it when taking a sample. 

In the actual boiler-test it is preferable to insert a 
T instead of this apparatus in the gas-stream, connect 
the gas apparatus to the free branch of this T, and 
draw the sample. In making connections with gas 
apparatus the air in the rubber connectors should be 
displaced with water by means of a medicine- 
dropper. 

In the Saxon coal-mines, zinc cans of ten liters 
capacity, of the form shown in Fig. 3, are used by 
Winkler for sampling the mine-gases; they are carried 
down filled with water and this allowed to run out, 
and the gas thus obtained brought into the laboratory 
and analyzed. Small samples of gas may very well be 
taken in tubes of 100 cc. capacity like Fig. 4, the 
ends of which are closed with rubber connectors and 
glass plugs. Rubber bags are not to be recommended 
for the collection and storage of gas for analysis, as 
they permit of the diffusion of gases, notably hydro- 
gen. 

3. Apparatus for Producing Suction. — I. Water- 
pumps — (#) Jet-pumps, depending for their action 
upon a considerable head of water, and (/;) those 
depending rather upon a sufficient fall of water. 



INTRODUCTION AND METHODS OF SAMPLING, 7 

(a) Jet-pi/mps.— The Richards' jet pump * is shown 
in section in Fig. 5 and much resembles a boiler 
injector; it consists of a water-jet w, a constriction or 
waist a, a waste-tube 0, and a tube for the inspiration 
of air. The jet of water forms successive pistons 
across a, drawing the air in with it and is broken up 
into foam by the zigzag tube 0. 

This pump is known in Germany as Muencke's, and 
in England as Wing's; Chapman's pump is also a 
modified form. 

It may be easily constructed in glass, the jets pass- 
ing through rubber stoppers which are wired down, 
thus admitting of adjustment to the conditions under 
which it has to work. 

(b) Fall-pumps. — Bunsen's pump, Fig. 6, consists 
of a wide glass tube A, drawn out at the bottom for 
connection with a |--inch lead pipe b, and at the top 
for connection w 7 ith c, the tube through which the air 
is drawn; this tube is usually fused in, although it 
may be connected with rubber; a is a rubber tube 
provided with screw cocks connected with the water- 
supply; d is connected with a mercury column, and 
the vessel B serves for the retention of any w r ater 
which might be drawn back into the apparatus evac- 
uated. 

The tube b for the best results should be 32 feet in 
length, equal to the height of a column of water sup- 
ported by the atmosphere, although for the ordinary 
purposes of gas-sampling it may be shorter. 

When water is admitted through a it fills b, acting 

* Richards, Am. Jour, of Science (3), 8, 412; Trans, Am. Inst. 
Min. Engrs., 6 : 492 (1874). 



8 



GAS AA J D FUEL ANALYSIS. 



as a continually falling piston drawing the current of 
air through e and its connections. These various 
forms of water-pumps should give a vacuum repre- 



WATER 



AIR 




FOAM 




Fig. 5. — Richards' Jet-pump. Fig. 6. — Bunsen's Pump. 

sented by the height of the barometer less the tension 
of aqueous vapor at the temperature at which they 
are used, or about 29 inches of mercury. 



INTRODUCTION AND METHODS OF SAMPLING. 9 

II. STEAM-PUMPS. — Kochinke describes the appa- 
ratus in use in the Muldner Hutten in Freiberg, 
shown at one-fifth size in Fig. 7. It consists of a 
glass tube drawn down to an opening 6 mm. in diam- 




Fig. 7. — Steam Air-pump. 

eter; concentric with this, and held in place by the 
washer a, is the steam-jet 2 mm. in diameter, passing 
through the cork b y the cement c, and covering d. It 
is connected with the steam-pipe at g by webbed 
rubber tubing/; the air enters at e. This is said to 
give very good results and be economical in use of 
steam. 

In case neither water nor steam be available, 
recourse must be had to the ordinary rubber syringe- 
bulbs, provided with suitable valves, obtainable at any 
rubber store, or to a bottle aspirator. This consists of 
two one-gallon bottles, provided with doubly perfor- 
ated rubber stoppers, carrying tubes of glass or lead 
bent at right angles. In each bottle one of these tubes 
passes nearly to the bottom, and these are connected 
together by a piece of rubber tubing a yard long, 
carrying a screw pinchcock. The other tube in each 
case stops immediately under the stopper. Upon 
filling one of the bottles with water, inserting the 
stopper and blowing strongly through the short tube, 
water will fill the long tubes thus forming a siphon, 



IO GAS AND FUEL ANALYSIS. 

and upon lowering the empty bottle, a current of air 
will be sucked in through the short tube originally 
blown into ; this may be regulated by the screw 
pinchcock. 



CHAPTER II. 

APPARATUS FOR THE ANALYSIS OF CHIMNEY- 

GASES. 

IN the writer's opinion the apparatus which is best 
adapted for this purpose is that of Orsat; it is readily 
portable, not liable to be broken, easy to manipulate, 
sufficiently accurate, and — in the modification about to 
be described — always ready for use, there being no 
stopcocks to stick fast. 

As the Bunte and Elliott apparatus are also used 
for this purpose, they too will be described. 

Fischer's apparatus, using mercury, is rather too 
difficult for the average engineer ; Hempel's apparatus 
for the analysis of illuminating-gas might also be used; 
it is, however, not customary. 

ORSAT APPARATUS. 

Description. — The apparatus Fig. 8, is enclosed in 
a case to permit of transportation from place to place; 
furthermore, the measuring-tube is jacketed with 
water to prevent changes of temperature affecting the 
gas-volume. The apparatus consists essentially of 
the levelling-bottle A, the burette £, the pipettes 
P\ P'\ P"\ and the connecting tube T. 

ii 



12 



GAS AND FUEL ANALYSIS. 



Manipulation. — The reagents in the pipettes should 
be adjusted in the capillary tubes to a point on the 
stem about midway between the top of the pipette 
and the rubber connector. This is effected by open- 
ing wide the pinchcock upon the connector, the 




Fig. 8. — Orsat's Gas Apparatus. 



bottle being on the table, and very gradually lower- 
ing the bottle until the reagent is brought to the point 
above indicated. Six inches of the tubing used corre- 
spond to but o.i cc, so that an error of half an inch 
in adjustment of the reagent is without influence 
upon the accuracy of the result. The reagents having 
been thus adjusted, the burette and connecting tube 
are completely filled with water by opening d and 
raising the levelling-bottle. The apparatus is now 



ANALYSIS OF CIIIMNE Y-GASES. 1 3 

ready to receive a sample of gas (or air for prac- 
tice). In case a flue- gas is to be analyzed d is con- 
nected with t, Fig. 2, A lowered and about 102 cc. 
of the gas forced over by opening h\ or d may 
be connected with aT joint in the gas-stream; the 
burette after filling is allowed to drain one minute by 
the sand-glass, c snapped upon its rubber tube, and 
the bottle A raised to the top of the apparatus. By 
gradually opening c the water is allowed to run into 
the burette until the lower meniscus stands upon the 
100 or o mark (according to the graduation of the 
apparatus). The gas taken is thus compressed into 
the space occupied by 100 cc, and by opening d the 
excess escapes. Open c and bring tlie level of the 
zvater in tlie bottle to the same level as tlie water in the 
burette and take the reading, which should be 100 cc. 
Special attention is called to this method of reading: 
if the bottle be raised, the gas is compressed; if 
lowered, it is expanded. 

Determination of Carbon Dioxide. — The gas to be 
analyzed is invariably passed first into pipette P\ con- 
taining potassium hydrate for the absorption of carbon 
dioxide, by opening e and raising A, The gas dis- 
places the reagent in the front part of the pipette, 
laying bare the tubes contained in it, which being 
covered with the reagent present a large absorptive 
surface to the gas; the reagent moves into the rear 
arm of the pipette, displacing the air over it into the 
flexible rubber bag which prevents its diffusion into 
the air. The gas is forced in and out of the pipette 
by raising and lowering^, the reagent finally brought 
approximately to its initial point on the stem of the 



14 GAS AND FUEL ANALYSIS. 

pipette, the burette allowed to drain one minute, and 
the reading taken. The difference between this and 
the initial reading represents the cubic centimeters of 
carbon dioxide present in the gas. To be certain that 
all the carbon dioxide is removed, the gas should be 
passed a second time into P' and the reading taken 
as before; these readings should agree within o. I per 
cent. 

Determination of Oxygen. — The residue from the 
absorption of carbon dioxide is passed into the second 
pipette, P" , containing an alkaline solution of potas- 
sium pyrogallate, until no further absorption will take 
place. The difference between the reading obtained 
and that after the absorption of carbon dioxide, repre- 
sents the number of cubic centimeters of oxygen 
present. 

Determination of Carbonic Oxide. — The residue 
from the absorption of oxygen is passed into the third 
pipette, P'" , containing cuprous chloride, until no 
further absorption takes place; that is, in this case 
until readings agreeing exactly (not merely to o. i) are 
obtained. The difference between the reading thus 
obtained and that after the absorption of oxygen, 
represents the number of cubic centimeters of carbonic 
oxide present. 

Determination of Hydrocarbons. — The residue 
left after all absorptions have been made may consist, 
in addition to nitrogen, the principal constituent, of 
hydrocarbons and hydrogen. Their determination is 
difficult for the inexperienced, and, if desired, a sample 
of the flue-gas should be taken, leaving as little water 



ANALYSIS OF CHIMNEY-GASES. 1 5 

in the apparatus as possible, and sent to a competent 
chemist for analysis. 

Accuracy. — The apparatus gives results accurate to 
0.2 of one per cent. 

Time Required. — About twenty minutes are re- 
quired for an analysis ; two may be made in twenty-five 
minutes, using two apparatus. 

Notes. — The method of adjusting the reagents is the 
only one which has been found satisfactory: if the 
bottle be placed at a lower level and an attempt made 
to shut the pinchcock c upon the connector at the 
proper time, it will almost invariably result in failure. 

The process of obtaining ioo cc. of gas is exactly 
analagous to filling a measure heaping full of grain and 
striking off the excess with a straight-edge; it saves 
arithmetical work, as cubic centimeters read off repre- 
sent percent directly. 

It often happens when e is opened, c being closed, 
that the reagent in P' drops, due not to a leak as is 
usually supposed, but to the weight of the column of 
the reagent expanding the gas. 

The object of the rubber bags is to prevent the 
access of air to the reagents, those in P n and P' n 
absorbing oxygen with great avidity, and hence if 
freely exposed to the air would soon become useless. 

Carbon dioxide is always the first gas to be removed 
from a gaseous mixture. In the case of air the per- 
centage present is so small, 0.08 to o. 1, as scarcely to 
be seen with this apparatus. It is important to use 
the reagents in the order given ; if by mistake the gas 
be passed into the second pipette, it will absorb not 
only oxygen, for which it is intended, but also carbon 



1 6 GAS AND FUEL ANALYSIS, 

dioxide; similarly if the gas be passed into the third 
pipette, it will absorb not only carbonic oxide, but 
also oxygen as well. 

The use of pinchcocks and rubber tubes, original 
with the author, although recommended by Naef,* is 
considered by Fischer, f to be inaccurate. The ex- 
perience of the author, however, does not support 
this assertion, as they have been found to be fully 
as accurate as glass stopcocks, and very much less 
troublesome and expensive. 

In case any potassium hydrate or pyrogallate be 
sucked over into the tube T or water in A, the analysis 
is not spoiled, but may be proceeded with by connect- 
ing on water at d, opening this cock, and allowing the 
water to wash the tubes out thoroughly. The addi- 
tion of a little hydrochloric acid to the water in the 
bottle A will neutralize the hydrate or pyrogallate, and 
the washing may be postponed until convenient. 

After each analysis the number of cubic centimeters 
of oxygen and carbonic oxide should be set down upon 
the ground -glass slip provided for the purpose. By 
adding these numbers and subtracting their sum from 
the absorption capacity (see Reagents) of each reagent, 
the condition of the apparatus is known at any time, 
and the reagent can be renewed in season to prevent 
incorrect analyses. 

BUNTE APPARATUS. 

Description. — The apparatus Fig. 9 consists of a 
burette — bulbed to avoid extreme length — provided 

* Wagner's Jahresb. 18S5, p. 423. 

f Technologic* d. Brennstoffe, foot note p. 295, 



ANALYSIS OF CHIMNEY-GASES. 



17 



at the top with a funnel F and three-way cocky, and 
a cock / at the bottom. These stopcocks are best 
of the Greiner and Friedrichs obliquely bored form. 
The burette is supported upon a retort- 
stand with a spring clamp. 

A "suction-bottle " S f an 8-oz. wide- 
mouthed bottle, fitted similarly to a 
wash-bottle, except that the delivery- 
tube is straight and is fitted with a 
four-inch piece of J-inch black rubber 
tubing, serves to withdraw the re- 
agents and water when necessary. A 
reservoir to contain water at the tem- 
perature of the room, fitted with along 
rubber tube, should be provided for 
washing out the reagents and filling 
the burette. 

Manipulation. — Before using the 
apparatus, the keys of the stopcocks 
should be taken out, wiped dry, to- 
gether with their seats, and sparingly 
smeared with vaseline or a mixture of 
vaseline and tallow and replaced. The Fig. 9.— Bunte's 
completeness of the lubrication can be Gas Apparatus - 
judged by the transparency of the joint, a thoroughly 
lubricated joint showing no ground glass. The 
burette is filled with water by attaching the rubber 
tube to the tip at / and opening the stopcocks at the 
top and bottom ; j is connected with the source whence 
the gas is to be taken, turned to communicate with 
the burette and opened, about 102 cc. of gas allowed 
to run in, and j and /closed. 



r 



l8 GAS AMD FUEL ANALYSIS. 

The cup F is filled with water to the 25-cc. mark,/ 
turned to establish communication between it and the 
burette, the burette allowed to drain one minute by 
the sand-glass, and the reading taken, the cup being 
refilled to the mark if necessary. The readings are 
thus taken under the same pressure each time, i.e., 
this column of water plus the height of the barometer; 
and as the latter is practically constant during the 
analysis, no correction need be applied, it being within 
the limits of error. 

Determination of Carbon Dioxide. — The " suc- 
tion-bottle " is connected with the tip of the burette, 
/ opened, and the water carefully sucked out nearly to 
/. The bottle is now disconnected, the burette dis- 
mounted from its clamp, using the cup as a handle, 
and the 25 cc. of water turned out. The tip is 
immersed under potassium hydrate contained in the 
No. 3 porcelain dish, and the cock / opened, then 
closed, and the tip wiped clean with a piece of cloth. 
The burette is now shaken, holding it by the tip and 
the cup, the thumbs resting upon j and /; more 
reagent is introduced, the absorption of the gas caus- 
ing a diminished pressure, and the operation repeated 
until no change takes place. The cup is now filled 
with water, j opened, and the reagent completely 
washed out into an ordinary tumbler placed beneath 
the burette. Four times filling of F should be suffi- 
cient for this purpose. The cup is now filled to the 
25-cc. mark, j opened, and the reading taken as 
before. 

The difference between this read in er and the initial 
represents the number of cubic centimeters of carbon 



ANALYSIS OF CHIMNEY-GASES. 19 

dioxide; this divided by the volume of the gas taken 
gives the per cent of this constituent. 

Determination of Oxygen. — The water is again 
sucked out, and potassium pyrogallate solution intro- 
duced, similarly to potassium hydrate; this is dis- 
placed by water, and the reading taken as before. 
The difference between this and the last reading is the 
volume of oxygen present. 

Determination of Carbonic Oxide. — The water is 
removed for a third time, and acid cuprous chloride 
solution introduced and the absorption made as before ; 
this is washed out, first with water containing a little 
hydrochloric acid to dissolve the white cuprous chlo- 
ride which is precipitated by the addition of water, 
and finally with pure water, and the reading taken as 
before. The difference between this and the preced- 
ing gives the volume of carbonic oxide present. 

Notes, — Especial care should be taken not to grasp 
the burette by the bulb, as this warms the gas and 
renders the readings inaccurate. The stopcocks can 
conveniently be kept in the burette by elastic bands 
of suitable size. When the apparatus is put away for 
any considerable time, a piece of paper should be 
inserted between the key and socket of each stopcock 
to prevent the former from sticking fast. To ascer- 
tain when the absorption is complete, the burette is 
mounted in its clamp and allowed to drain until the 
meniscus is stationary, the dish containing the reagent 
raised until the tip is covered, /opened, and any change 
in level noted. If the meniscus rises, the absorption 
is incomplete and must be continued; if it remains 
stationary or falls, the absorption may be regarded as 



20 GAS AND FUEL ANALYSIS, 

finished. In case the grease from the stopcocks 
becomes troublesome inside the burette, it may be 
removed by dissolving it in chloroform and washing 
out with alcohol and then with water. The object in 
sucking the water not quite down to /, thus leaving a 
little water in the burette, is to discover if / leaks, the 
air rushing in causes bubbles. 

The object in washing out each reagent and taking 
all readings over water is to obviate corrections for 
the tension of aqueous vapor over potassium hydrate, 
hydrochloric acid, or any of the reagents which might 
be employed. The tension of aqueous vapor over 
seven per cent caustic soda is less than over water. 

Accuracy and Time Required. — The apparatus is 
rather difficult to manipulate, but fairly rapid — about 
twenty-five minutes being required for an analysis — 
and accurate to one tenth of one per cent. 

ELLIOTT APPARATUS. 

Description. — The apparatus Fig. 10 consists of a 
burette holding ioo cc. graduated in tenths of a cubic 
centimeter and bulbed like the Bunte apparatus — the 
bulb holding about 30 cc. ; it is connected with a 
levelling-bottle similar to the Orsat apparatus. The 
top of the burette ends in a capillary stopcock, the 
stem of which is ground square to admit of close con- 
nection with the "laboratory vessel,' ' an ungraduated 
tube similar to the burette, except of 125 cc. capacity. 
The top of this "vessel " is also closed with a capil- 
lary stopcock, carrying by a ground-glass joint a 
thistle-tube F } for the introduction of the reagents. 
The lower end of this " vessel M is closed by a rubber 



ANALYSIS OF CHIMNEY-GASES. 



21 



n 



75 



stopper carrying a three-way cock o> and connected 
with a levelling-bottle D. The 
burette and vessel are held upon a 
block of wood — supported by a ring 
stand — by fine copper wire tight- 
ened by violin keys. 

Manipulation. — The ground-glass 
joints are lubricated as in the Bunte 
apparatus. The levelling- bottles are 
filled with water, the stopcocks 
opened, and the bottles raised until 
the water flows through the stop- 
cocks m and n. m is connected 
with the source whence the gas to 
be analyzed is to be taken, n closed, 
D lowered and rather more than ioo 
cc. drawn in, and m closed, n is 
opened, D raised and E lowered, 
nearly ioo cc. of gas introduced, 
and n closed ; by opening in and 
raising D the remainder of the gas 
is allowed to escape, the tubes being 
filled with water and in closed, n is 
opened and the water brought to 
the reference-mark; the burette is 
allowed to drain one minute, the 
level of the water in E is brought 

to the same level as in the burette, FlG * IO *~" Elliott 

, Gas Apparatus. 

and the reading taken. 

Determination of Carbon Dioxide — By raising E, 

opening /z, and lowering D, the gas is passed over into 

the laboratory vessel; F is filled within half an inch 



" , ^- 



l\ 



El 



,^/ 



22 GAS AND FUEL ANALYSIS. 

of the top with potassium hydrate, o closed, m opened, 
and the reagent allowed to slowly trickle in. A No. 3 
evaporating-dish is placed under o, and this turned to 
allow the liquid in the laboratory vessel to run into 
the dish. At first this is mainly water, and may be 
thrown away; later it becomes diluted reagent and 
may be returned to the thistle-tube. When the 
depth of the reagent in the thistle-tube has lowered 
to half an inch, it should be refilled either with fresh 
or the diluted reagent and allowed to run in until the 
absorption is judged to be complete, and the gas 
passed back into the burette for measurement. To 
this end close and then m, raise E, open n, and 
force some pure water into the laboratory vessel, thus 
rinsing out the capillary tube. Now raise D and lower 
E, shutting n when the liquid has arrived at the refer- 
ence-mark. The burette is allowed to drain a minute, 
the level of the water in the bottle E brought to the 
same level as the water in the burette, and the reading 
taken. 

Determination of Oxygen. — The manipulation is 
the same as in the preceding determination, potassium 
pyrogallate being substituted for potassium hydrate; 
the apparatus requiring no washing out. 

Determination of Carbonic Oxide. — The labora- 
tory vessel, thistle-tube, and bottle if necessary, are 
washed free from potassium pyrogallate and the 
absorption made with acid cuprous chloride similarly 
to the determination of carbon dioxide. The white 
precipitate of cuprous chloride may be dissolved by 
hydrochloric acid. 



ANALYSIS OF CHIMNEY-GASES. 23 

Accuracy and Time Required. — The apparatus is 
as accurate for absorptions as that of Orsat; it is 
stated to be much more rapid — a claim which the writer 
cannot substantiate. It is not as portable, is more 
fragile, and more troublesome to manipulate, and as 
the burette is not jacketed it is liable to be affected 
by changes of temperature. 

Notes. — In case at any time it is desired to stop 
the influx of reagent, o should be closed first and 
then M\ the reason being that the absorption may 
be so rapid as to suck air in through 0, m being 
closed. 

The stopcock should be so adjusted as to cause the 
reagent to spread itself as completely as possible over 
the sides of the burette. 

By the addition of an explosion-tube it is used for 
the analysis of illuminating-gas,* bromine being used 
to absorb the " illuminants. , ' Winkler f has shown 
that this absorption is incomplete, and Hempel % that 
explosions of hydrocarbons made over water are in- 
accurate, so that the apparatus can be depended upon 
to give results upon methane and hydrogen only within 
about two per cent. 

* Mackintosh, Am. Chem. Jour. 9, 294. 
\ Zeitsch. f. Anal. Chem. 28, 286. 
% Gasanalytische Methoden, p. 102. 



CHAPTER III. 
MEASUREMENT OF TEMPERATURE. 

In the majority of cases, the ordinary mercurial 
thermometer will serve to determine the temperature 
of the chimney-gases. It should not be inserted naked 
into the flue, but be protected by a bath of cylinder, 
or raw linseed oil, contained in a brass or iron tube. 
These tubes may be half an inch inside diameter and 
two to three feet in length. Temperatures as high as 
62 5 C. have been observed in chimneys; this lasts of 
course but for a moment, but would be sufficient to 
burst the unprotected thermometer. 

For the observation of higher temperatures, recourse 
must be had to the " high-temperature thermom- 
eters, " filled with carbon dioxide under a pressure of 
about one hundred pounds, giving readings to 550 C* 
These may be obtained of the dealers in chemical 
apparatus; some require no bath, being provided 
with a mercury-bath carefully contained in a steel 
tube, and the whole enclosed in a bronze tube.f 

* Those made by W. Apel, Gottingen, Germany, are about three 
feet long, the scale occupying about one foot, thus avoiding the 
necessity of withdrawing the thermometer from the bath for 
reading. 

f Those made by the Hohmann and Maurer Co., Brooklyn, 
N. Y. 

24 



MEASUREMENT OF TEMPERATURE, 2$ 

These thermometers should be tested from time to 
time either by comparison with a standard or by inser- 
tion in various baths of a definite temperature. Some 
of the substances used for these baths are: water, boil- 
ing-point ioo° ; naphthalene, Bpt. 2 1 9 ; benzophenon, 
Bpt. 306 ; and sulphur,* Bpt. 445 . Care should be 
taken that the bulb of the thermometer does not dip 
into the melted substance, but only into the vapor, 
and that the stem exposure be as nearly as possible 
that in actual use. 

For the measurement of temperatures beyond the 
range of these thermometers the Le Chatelier thermo- 
electric pyrometer may be used. This consists of a 
couple formed by the junction of a platinum and 
platinum- 10$ rhodium wire, passing through fire-clay 
tubes in a porcelain or iron envelope and connected 
with a galvanometer. The hotter the junction is 
heated the greater the current and the galvanometer 
deflection; this latter is determined for several points, 
naphthalene, sulphur, and copper, Mpt. 1095 C, or 
even platinum, 1760 C, and a plot made with gal- 
vanometer-readings as abscissae and temperatures as 
ordinates. From this the temperature corresponding 
to any deflection is readily obtained. 

The exact description of the instrument and details 
of calibration are, however, beyond the scope of this 
work, and the student is referred for these to articles 
by Le Chatelier, Societe Technique de l'lndustrie du 
Gaz, 1890, abstracted in Jour. Soc. Chem. Industry, 

* In testing the H. & M. thermometers in sulphur-vapor, the 
bronze tube should be prevented from corrosion by the vapor by 
a glass envelope. 



26 



GAS AND FUEL ANALYSIS. 



9, 326, and Holman, Proc. Am. Academy, 1895, p. 

234. 

An error of 5 ° in the reading of the thermometer 

affects the final result by about 20 calories. 

In case neither of these methods be available nor 




Fig. 11. — Melting-point Boxes. 



applicable, use may be made of the melting-points 
of certain metals or salts contained in small cast-iron 
boxes, Fig. 1 1. The melting-points of certain metals 
and salts are given in Table VII. 



CHAPTER IV. 
CALCULATIONS. 

As has been already stated in the Introduction, the 
object of analyzing the flue-gases is to ascertain, first, 
the completeness of the combustion, especially the 
amount of air which has been used or the " pounds of 
air per pound of coal," and second, the amount of 
heat passing up chimney. 

I. To Ascertain the Number of Pounds of Air 
per Pound of Coal. — A furnace-gas gives 11.5$ CO a , 
7.4$ O, 0.9^ CO, and 80.2$ N. Data: atomic weights, 
O = 16, C=-I2; weight liter C0 2 = 1.966 grs., of 
O, 1.43 grs., of CO, 1.25 1 grs. Find the number of 
grams of each constituent in 100 liters of the furnace- 
gas, and from this the weight of carbon and weight of 
oxygen. 11.5 (liters C0 2 ) X 1.97 (wt. liter C0 2 ) = 

32/ 2 \ 
22.66 grms. C0 2 ; now — ^TyS") °f this ls oxygen = 

16.41 grms., 6.25 grms. is carbon. The weight of 
free oxygen is 7.4 X 1.43 = 10.58 grms. The weight 
of carbon and oxygen in the carbonic oxide is 0.9 X 

1.25 = 1. 12 grms. CO. Now -(——] is oxygen or 0.64 

grm., and 0.48 grm. is carbon. There are then pres- 
ent in 100 liters of the gas 27.63 grms. oxygen and 
6.73 grms. carbon; corresponding to 119.6 grms. air 

27 



28 GAS AND FUEL ANALYSIS. 

to 6.73 grms. carbon, air being 23.1$ oxygen by 

grms. ) . grm. ) 

weight; or 17.77 „ r air per > carbon. If 

the coal be 83$ carbon, this figure must be diminished 
accordingly, giving in this case 14.75 lbs. air per lb. 
of coal. Theory requires 11.54 lbs. air per lb. of car- 
bon, but in practice the best results are obtained by 
increasing this from 50$ to 100$. * 

2. To Ascertain the Quantity of Heat Passing 
up Chimney — Determine the volume of gas generated 
from one kilo of coal when burned so as to produce 
the 'gas the analysis of which has just been made 
according to the directions given. The chemical 
analysis of the coal is as follows: moisture 1.5$, 
sulphur 1.2$, carbon 83$, hydrogen 2.5$, ash 1 1. 40, 
oxygen and nitrogen (by difference) 0.4$. Then 
there are in one kilo of coal 830 grms. carbon, of 
this suppose but 800 to be burned, the remaining 30 
grms. going into the ash; of the 800 grms. 625/673 
or 743 grms. produced carbon dioxide, and 48/673 
or 57 grms. produced carbonic oxide. From 6.25 
grms. carbon were produced 1 1 . 5 liters carbon di- 
oxide in the problem in 1 ; hence 743 grms. would 
furnish 1367 liters. 6.25 : 743 : : 1 1.5 : y. y= 1367. 
Similarly 57 grms. carbon would furnish 107.4 liters 
carbonic oxide. 0.48 : 57: : 0.90 : z. ,0=107.4. The 
volume of oxygen can be found by the proportion 
1 1. 5 (0 CO a ): 7.4(00):: 1367:*. ^=880 liters. In 
the same manner the nitrogen is found to be 9535 
liters. 1 1.5: 80.2 :: 1367: «. // = 9535. One kilo of 
coal under these conditions furnishes 1.367 cu. meter 

*Scheurer-Kestner, Jour. Soc. Chem. Industry, 7, 616. 



CA L CULA TIONS. 29 

carbon dioxide, 0.107 c. m. carbonic oxide, 0.880 
c. m. oxygen, and 9.535 c. m. nitrogen. 

The quantity of heat carried off by each gas is its 
rise of temperature X its weight X its specific heat, 
The specific heats of the various gases are shown in 
the table below, and for facility in calculation, a column 
is given obtained by multiplying the weight by the 
specific heat; multiplying the volumes obtained in the 
previous calculation by the numbers in this column 
and by the rise in temperature gives the number of 
calories (C) that each gas carries away. 

TABLE OF SPECIFIC HEATS OF VARIOUS GASES.* 

en c „ , Wt. of Cu. M. Sp. Heat X 

Name of Gas. Sp. Heat. T _ __*; , „ ._ Log. 

Kg. Wt. ofCu. M. & 

Carbon dioxide (io°-350°). 0.234 r -97 0.463 9.6656 

" monoxide 0.245 1.26 0.308 9.4886 

Oxygen 0.217 1-43 0.311 9.4928 

Nitrogen. ,0 0.244 1.26 0.306 9.4857 

Aqueous vapor 0.480 0.80 0.387 9-5877 

In the test the average temperature of the escaping 
gases was 275 C. ; that of the air entering the grate 
was 2 5 C, a rise of temperature of 250 C. As 
shown by the wet-and-dry-bulb thermometer, the air 
was 50 per cent saturated with moisture. 

The calculation of the heat carried away is then for: 

Cu. m. c. 

Carbon dioxide 1-367 X 250 X 0.463 = 158.2 

Carbonic oxide o. 107 X " X 0.308 = 8.2 

Oxygen 0.880 X " X o 311= 68.4 

Nitrogen 9-535 X " X 0.306 = 729.3 

Total 11.889 964.1 

•——=——— — ■ — . __ — . — ■ 

* Fischer, Tech. d. Brennstoffe, p. 267. 



30 GAS AND FUEL ANALYSIS. 

There is, however, another gas passing up chimney 
of which we have taken no cognizance, namely, water- 
vapor; this comes from the moisture in the coal, from 
the combustion of hydrogen in the coal, and from the 
air entering the grate; its volume is calculated as 
follows: 

The moisture in the coal as found by chemical 
analysis was 1.5^ = 0.015 kg.; the hydrogen in the 
coal was 2.5$ = 0.025 kg. The amount of water this 
forms when burned is nine times its weight, 0.025 kg. 
X 9 = 0.225 kg. The moisture in the air entering the 
grate would be, if completely saturated, 22.9 grams 
per cubic meter, as shown by Table I ; it was, how- 
ever, but 50$ saturated. The quantity is then, the 
volume of air used per kilogram of coal X moisture 
contained in it, or 11.889 X 22.9 X 0.50 = 0,137 kg. 
The weight of aqueous vapor passing up chimney per 
kilogram of coal is 0.015 -f- 0.225 -j- O.137 = 0.377 
kg. ; the quantity of heat that this carries off is 0.377 
X 250 X 0.480 = 45.2 C. The total quantity of heat 
passing up chimney is then 1009.3 C. The heat of 
combustion of this coal as found by Mahler's calori- 
metric bomb was 7220 C. ; hence the percentage of 
heat carried off is 1009/7220 = 14$. 

The preceding calculations though correct are 
tedious, so much so, as to almost preclude their use 
for an hourly observation of the firing. They should 
be employed, however, in making the final calculation 
of a boiler-test, using the averages obtained. 

In rapid work the following formula will be found 
more applicable: Let o and n represent the percent- 
ages of oxygen and nitrogen found in the chimney- 



CA LCULA TIONS. 3 1 

gas; then the ratio of the air actually used to that 
theoretically necessary is expressed by the formula, 

21 



21 



- m 

\ n. / 



Applying it in the case of the flue-gas given, it 
becomes 

21 21 



o T ( 79 X 7- 4^ 13-7 
21 - \~SS^ 



= 1. 533 ratio, 



Multiplying this by 11.54, the theoretical number of 
pounds of air per pound of carbon, we obtain 17.69 as 
against 17.77 on page 28. 

• Lunge * has given a shorter method for the deter- 
mination of the quantity of heat passing up chim- 
ney, and one which does not involve the analysis of 
the coal. 

One kilogram of pure carbon yields, when burned, 
1.854 cubic meters of carbon dioxide under standard 
conditions and evolves 8080 calories. By the analysis 
of the gases we obtain the percentages of carbon 
dioxide, oxygen, and nitrogen. Let k = per cent of 
carbon dioxide, then 100 — k represents the per cent 
of nitrogen and oxygen together. Let 1.854 cu. m. 
represent this per cent of carbon dioxide, then x, the 
volume of the nitrogen and oxygen, may be found by 
the proportion 1.854: k\\ x\ (100 — k). 

(100 — k) 
.\ * = 1.854 - k - ; . 

* Zeit. f. angewandte Chemie, T889, 240. 



3 2 GAS AND FUEL ANALYSIS, 

Let / be the temperature of the air entering the 
grate, and t' that of the gases in the chimney; then 
t' — t represents the rise of temperature. Let c repre- 
sent the specific heat of a cubic meter of carbon dioxide 
= 0.46, p. 29, and c' that of a cubic meter of ni- 
trogen = 0.31. Then the loss of heat is represented 
by the formula 

1. 854 (*' - ty + 1.854 C-^fAv - ty. 



k 

The percentage of heat lost is then 

Loss of heat X 100 
8080 * 

Substituting in this formula for k, I.I..5, t' — t, 250 , 
we obtain 



(1.854X250)046)+ 1. 8S4(yyt|)(25o)(o.3i) == 1319. 

= 16.3& 



Loss of heat = 

3.5 

5 
1319 X IQQ 
8080 

loss of heat as against 14^ on page 30. 

This formula gives results which are usually 2 to 2\ 
per cent too high. 

Determination of Loss Due to Formation of Car- 
bonic Oxide. — On page 28 we see that 57 grams of 
carbon burned to carbonic oxide; for every gram of 
carbon burned to carbonic oxide there is a loss of 
5.66 C, in this case a loss of 323 C. The heating 
value of the coal is 7220 C, hence the loss is 4.5 per 
cent. 



CALCULATIONS. 33 

Determination of the Loss Due to Unconsumed 
Fuel. — The per cent of carbon in the ash being 
determined by chemical analysis, and the weight of 
the ash being known, the weight of the unburned car- 
bon can be determined. This can be then calculated 
as coal, which divided by the weight of coal fired 
gives the loss due to this source. This loss varies 
from 5 to 7 per cent. This should be taken cogni- 
zance of in calculating the volume of flue-gases formed 
from one kilogram of coal. 



CHAPTER V. 

REAGENTS AND ARRANGEMENT OF THE 
LABORATORY. 

THE reagents used in gas-analysis are comparatively 
few and easily prepared. 

Hydrochloric Acid, Sp. gr. i.io. — Dilute "muri- 
atic acid " with an equal volume of water. In addi- 
tion to its use for preparing cuprous chloride, it finds 
employment in neutralizing the caustic solutions which 
are unavoidably more or less spilled during their use. 

Acid Cuprous Chloride. — The directions given in 
the various text-books being troublesome to execute, 
the following method, which is simpler, has been 
found to give equally good results. Cover the bottom 
of a two-liter bottle with a layer of copper oxide or 
" scale f in. deep, place in the bottle a number of 
pieces of rather stout copper wire reaching from top 
to botto7n, sufficient to make a bundle an inch in 
diameter, and fill the bottle with common hydrochloric 
acid of i.io sp. gr. The bottle is occasionally shaken, 
and when the solution is colorless, or nearly so, it is 
poured into the half-liter reagent bottles, containing 
copper wire, ready for use. The space left in the 
stock bottle should be immediately filled with hydro- 
chloric acid (i.io sp. gr.). 

34 



REAGENTS AND LABORATORY, 35 

By thus adding acid or copper wire and copper 
oxide when either is exhausted, a constant supply of 
this reagent may be kept on hand. 

The absorption capacity of the reagent per cc. is, 
according to Winkler, 15 cc. CO; according to 
Hempel 4 cc. The author's experience with Orsat's 
apparatus gave 1 cc. 

Care should be taken that the copper wire does not 
become entirely dissolved and that it extend from the 
top to the bottom of the bottle; furthermore the 
stopper should be kept thoroughly greased the moref 
effectually to keep out the air, which turns the solution; 
brown and weakens it. 

Ammoniacal Cuprous Chloride. — The acid cu- 
prous chloride is treated with ammonia until a faint 
odor of ammonia is perceptible; copper wire should 
be kept in it similarly to the acid solution. This 
alkaline solution has the advantage that it can be 
used when traces of hydrochloric acid vapors might 
be harmful to the subsequent determinations, as, for 
example, in the determination of hydrogen by absorp- 
tion with palladium. It has the further advantage 
of not soiling mercury as does the acid reagent. 

Absorption capacity, 1 cc. absorbs 1 cc. CO. 

Cuprous chloride is at best a poor reagent for the 
absorption of carbonic oxide ; to obtain the greatest 
accuracy where the reagent has been much used, the 
gas should be passed into a fresh pipette for final 
absorption, and the operation continued until two 
consecutive readings agree exactly. The compound 
formed by the absorption — possibly Cu,COCl 2 — is very 
unstable, as carbonic oxide may be freed from the 



36 GAS AND FUEL ANALYSIS. 

solution by boiling or placing it in vacuo; even if it 
be shaken up with air, the gas is given off, as shown 
by the increase in volume and subsequent diminution 
when shaken with fresh cuprous chloride. 

Potassium Hydrate. — (a) For carbon dioxide de- 
termination, 500 grams of the commercial hydrate is 
dissolved in 1 liter of water. 

Absorption capacity, 1 cc. absorbs 40 cc, C0 2 . 

(b) For the preparation of potassium pyrogallate 
for special work, 120 grams of the commercial hydrate 
is dissolved in 100 cc. of water. 

Potassium Pyrogallate. — Except for use with the 
Orsat or Hempel apparatus, this solution should be 
prepared only when wanted. The most convenient 
method is to weigh out 5 grams of the solid acid upon 
a paper, pour it into a funnel inserted in the reagent 
bottle, and pour upon it 100 cc. of potassium hydrate 
(a) or (b). The acid dissolves at once, and the solution 
is ready for use. 

If the percentage of oxygen in the mixture does 
not exceed 28, solution (a) may be used ;* if this 
amount be exceeded, (V) must be employed. Other- 
wise carbonic oxide may be given off even to the 
extent of 6 per cent. 

Attention is called to the fact that the use of potas- 
sium hydrate purified by alcohol has given rise to 
erroneous results. 

Absorption capacity , 1 cc. absorbs 2 cc. O. 

Sodium Hydrate. — Dissolve the commercial hy- 
drate in three times its weight of water. This may be 

* Clowes, Jour. Soc. Chem. Industry, 15, 170. 



REAGENTS AND LABORATORY, 37 

employed in all cases where solution (a) of potassium 
hydrate is used. The chief advantage in its use is its 
cheapness, it costing but one tenth as much as potas- 
sium hydrate, a point to be considered where large 
classes are instructed. Sodium pyrogallate is, how- 
ever, a trifle slower in action than the corresponding 
potassium salt. 

ARRANGEMENT OF THE LABORATORY. 

The room selected for a laboratory for gas-analysis 
should be w r ell lighted, preferably from the north and 
east. To prevent changes in temperature it should 
be provided with double windows, and the method of 
heating should be that which will give as equable a 
temperature as possible. In the author's laboratory, 
instead of the usual tables, shelves are used, 18 inches 
wide and i^ inches thick, best of slate or soapstone, 
firmly fastened to the walls, 30 inches from the floor; 
the Orsat apparatus, when not in use, may be sus- 
pended from these. The reagents are contained in 
half-liter bottles fitted with rubber stoppers, placed 
upon a central table convenient to all. Here are 
found scales, funnels and graduates for use in making 
up reagents. Distilled water is piped around to each 
place by -J-inch tin pipe and ^-inch rubber tubing 
from a J-inch "main," being supplied at the tem- 
perature of the room from bottles placed about six 
feet above the laboratory shelves. A supply of a 
gallon per day per student should be provided. 

At the right of each place is fixed a sand-glass of 
cylindrical rather than conical form, graduated to 
minutes for the draining of the burettes. The "egg- 



38 GAS AND FUEL ANALYSIS. 

timers " found in kitchen-furnishing stores serve the 
purpose admirably. 

" Unknown gases " for analysis are best contained 
in a Muencke double aspirator, Fig. 12, where they 



Fig. 12. — Muencke's Aspirator. 

can be thoroughly mixed before distribution and con- 
veyed by a pipe to the central table. 

Finally, the laboratory should contain a stone-ware 
sink provided with an efficient trap of the same 
material, to prevent mercury from being carried into 
and corroding the lead waste-pipes. 

Drawers should be provided with compartments for 
various sizes of rubber connectors, pinchcocks, glass 
tubing, stoppers and fittings, and tools. When work- 
ing with the Orsat apparatus alone, three feet of shelf 



REAGENTS AND LABORATORY. 39 

space may be allowed to each student; when using this 
with another, as, for example, the Bunte, another 
foot should be added. 

The course which the writer has been in the habit 
of giving to the Mechanical and Electrical Engineers 
embraces two exercises in the laboratory of two hours 
each, supplemented with four hours of lectures. The 
students in the laboratory make an analysis of air and 
an u unknown' furnace-gas, take and analyze an 
actual sample of chimney-gas, and make the calculation 
of heat lost and air used. In the lectures, the subject 
of gas-analysis and its other applications, and of fuels, 
their origin, description, preparation, analysis, and 
determination of heating value, are described. 



CHAPTER VI. 

FUELS— SOLID, LIQUID, AND GASEOUS: THEIR 
DERIVATION AND COMPOSITION. 

The substances employed as fuels are: 

a. SOLID FUELS. — Wood, peat, brown, bituminous 
and anthracite coal, charcoal, coke, and oftentimes 
various waste products, as sawdust, bagasse, straw, 
and spent tan. 

b. Liquid FUELS. — Crude petroleum and various 
tarry residues. 

c. GASEOUS FUELS. — Natural gas, producer, blast- 
furnace, water, and illuminating gas. 

The essential constituents in all these are carbon and 
hydrogen; the accessory, oxygen, nitrogen, and ash; 
and the deleterious, water, sulphur, and phosphorus. 

a. Solid Fuels. 

Wood is composed of three substances — cellulose, 
or woody fibre (C 6 H 10 O 6 ) M ; the components of the sap, 
the chief of which is lignine, a resinous substance of 
identical formula with cellulose; and water. The 
formation of cellulose from carbon dioxide and water 
may be represented by the equation 

6CO I +5H i O = C.H 1 .O i + 60 i . 

The amount of water which wood contains determines 
its value as a fuel. This varies from 29 per cent in ash 

40 



FUELS—SOLID, LIQUID, AND GASEOUS. 4* 

to 50 per cent in poplar; it varies also with the season 
at which the wood is cut, being least when the sap is in 
the roots — in December and January. This difference 
may amount to 10 per cent in the same kind of wood. 

The harder varieties of wood make the best fuel, a 
cord of seasoned hardwood being about equal to a ton 
of coal. Yellow pine, however, has but half this 
value; the usual allowance in a boiler-test is 0.4 the 
value of an equal weight of coal. 

The ash of wood is mainly potassium carbonate, 
with traces of other commonly occurring substances, 
as lime, magnesia, iron, silica, and phosphoric acid. 

The percentage composition of wood may be con- 
sidered as approximately, 

Water. Carbon. Hydrogen. Oxygen. Ash. Sp. Gr. 

20 39 4.4 35.6 I 0.5.* 

When burned it yields about 4000 C. per kilo, and 
requires 6 times its weight of air or 9.22 cu. m. (148 
cu. ft. per pound) for its combustion. 

Peat, though finding considerable application in 
Europe, is but little used in this country. It is pro- 
duced by the slow decay under water of certain swamp 
plants, more especially the mosses (Sphagnacese), 
evolving methane (CH 4 ) (marsh-gas) and carbon diox- 
ide (CO,). 

It contains considerable moisture, from 20 to 50 
per cent, and 10 per cent even when " thoroughly 
dry/' Thirty per cent of its available heat is em- 
ployed in evaporating this moisture. The high con- 
tent of ash, from 3 to 30 per cent, averaging 15 per 
cent, also diminishes its value as a fuel. 

* Mills & Rowan, Fuels, p. n. 



42 GAS AND FUEL ANALYSIS. 

The ash of peat differs from that of wood in contain- 
ing little or no potassium carbonate. 

The percentage composition of peat may be consid- 
ered as approximately, 

Water. Carbon. Hydrogen. Oxygen. Nitrogen. Ash. Sp. Gr. 
16.4 41.0 4.32 3.8 2.6 II. 9 1.05. 

Such peat is about equivalent to wood in its heating 
effect, one pound evaporating from 4.5 to 5 pounds 
of water. 

Coal. — Geologists tell us that coal was probably 
produced by the decay under fresh water of plants 
belonging principally to the Conifer, Fern and Palm 
families; these flourished during the Carboniferous 
Age to an extent which they never approached before 
or since. Representatives of the last family, which 
it is thought produced most of the coal, have been 
found 2 to 4 feet in diameter and 80 feet in height. 

By their decay, carbon dioxide " choke-damp/' 
marsh-gas " fire-damp," and water were evolved. 
The change might be represented by the equation 

6C 6 H 10 6 = ;C0 2 + 3 CH 4 + i 4 H 2 + C 26 H. i0 O,- 

Cellulose. Bituminous Coal. 

Some idea of the density of the vegetation and the 
time required may be obtained from the fact that it 
has been calculated that 100 tons of vegetable matter 
— the amount produced per acre per century — if com- 
pressed to the specific gravity of coal and spread over 
an acre would give a layer less than 0.6 of an inch 
thick. Now four fifths of this is lost in the evolution 
of the gaseous products, giving as a result an accumu- 



FUELS— SOLID, LIQUID, AND GASEOUS. 43 

lation of one eighth of an inch per century, or one foot 
in 10,000 years. * 

Brown Coal or Lignite may be regarded as forming 
the link between wood and coal; geologically speaking 
it is of later date than the true coal. Most of the coal 
west of the Rocky Mountains is of this variety. 

As its name denotes, it generally is of brown color 
— although the western coal is black — and has a con- 
choidal fracture. It contains a large quantity of 
water when first mined, as much as 60 per cent, and 
when " air-dry " from 15 to 20 per cent. The per 
cent of ash is also high, from 1 to 20 per cent. 

The percentage composition of brown coal may be 
considered as approximately, 

Water. Carbon. Hydrogen. Oxygen and Nitrogen. Ash. Sp. Gr. 

18.O 50.9 4.6 16.3 I0.2 1.3. 

Bituminous Coal. — This is the variety from which all 
the following coals are supposed to have been formed, 
by a process of natural distillation combined with pres- 
sure. According to the completeness of this process 
we have specimens which contain widely differing quan- 
tities of volatile matter. This forms the true basis for 
the distinguishing of the varieties of coal. In ordinary 
bituminous coal this volatile matter amounts to 30 or 
40 per cent. Three varieties of bituminous coal are 
ordinarily distinguished, as follows: 

Dry or non-caking — those which burn freely with but 
little smoke and — as the name denotes — do not cake 

* In case the student desires to follow in a more extended 
manner the geology of coal, reference may be had to Le Conte's 
" Elements of Geology," pp. 345-414, 3d ed, 



44 GAS AND FUEL ANALYSIS. 

together when burned. The coals from Wyoming 
are an example of this class. 

Caking — those which produce some smoke and cake 
or sinter together in the furnace. An example of 
these is the New River coal. 

Fat or Long-flaming — those producing much flame 
and smoke and do or do not cake in burning; volatile 
matter 50 per cent or more. Some of the Nova 
Scotia coals belong to this class. 

Bituminous coal varies much in its composition — is 
black or brownish black, soft, friable, lustrous, and of 
specific gravity of 1.25 to 1.5. 

Moisture varies from 0.25 to 8 per cent, averaging 
about 5. 

The percentage composition of bituminous coal may 
be considered as approximately,* 

Water. Carbon. Hydrogen. Oxygen. Nitrogen. Ash. Sulphur. 
0.6 80.5 4.9 5.4 2.1 5.8 0.7. 

Semi-Bituminous or Semi-Anthracite Coal is upon 
the border-line between the preceding and the follow- 
ing variety; it is harder than bituminous, contains 
less volatile matter (15 to 20 per cent), and burns 
with a shorter flame. An example of this is the 
Pocahontas coal. 

The percentage composition of semi-bituminous and 
semi-anthracite coal may be considered to be appioxi- 
mately,* 

Water. Carbon. Hydrogen. Oxygen. Nitrogen. Ash. Sulphur. 
1.8 77-4 4.7 3-7 2.0 9.5 0.9. 

Anthracite Coal is the hardest, most lustrous, and 
densest of all the varieties of coal, having a specific 

* H. J. Williams, 



FUELS—SOLID, LIQUID, AND GASEOUS. 45 

gravity of 1.3 to 1 . 75 ; it contains the most carbon 
and least hydrogen and volatile matter (5 to 10 per 
cent). It has a vitreous fracture and kindles with 
difficulty, burning with a feeble flame, giving little or 
no smoke and an intense fire. The Lehigh coal is an 
excellent example of this class. 

The percentage composition of anthracite coal may 
be considered as approximately,* 

Water. Carbon. Hydrogen. Oxygen. Nitrogen. Ash. Sulphur. 
3.2 82.4 2.5 2.7 0.8 7.8 O.6. 

The ash of coal varies from 1 to 20 per cent and is 
mainly clay — silicate of aluminium — with traces of 
lime, magnesia, and iron. When coal is burned it 
yields from 7500 to 8000 C. and requires about 12 times 
its weight of air, 18.44 cu. m. per kilo or 296 feet per 
pound. For the greatest economy Scheurer-Kestner f 
found that this should be increased from 50 to 100 
per cent. 

Charcoal is prepared by the distillation or smoulder- 
ing of wood, either in retorts, where the valuable 
by-products are saved, or in heaps. It should be 
jet-black, of bright lustre and conchoidal fracture. 

When wood is charred in heaps only about 20 per 
cent of its weight in charcoal is obtained — 48 bushels 
per cord, or about half the percentage of carbon. 
When retorts or kilns are employed, the yield is in- 
creased to 30 per cent, and 40 per cent of pyroligneous 
acid of 10 per cent strength, with 4 per cent of tar, 
are obtained. 

*H. J. Williams. 

\ Jour. Soc. Chem. Industry, 7, 616, 



4& GAS AND FUEL ANALYSIS. 

The percentage composition of wood-charcoal may be 
considered as approximately, 

Carbon. Ash. Sp. Gr. 

97.O 3.0 0.2 

Coke is prepared by the distillation of bituminous 
coal in ovens; these are of two types, those in which 
the distillation-products are allowed to escape — the 
" beehive " ovens — and those in which they are care- 
fully saved, as the Otto-Hoffman, Semet*Solvay, 
Simon-Carves', and others. 

From 63 to 65 per cent of the w T eight of the coal is 
obtained as coke in the <4 beehive " ovens, while in 
the Semet-Solvay 80 per cent is obtained, together 
with by-products, increasing the total value of 
the output nearly sevenfold. Good coke should 
possess a silvery lustre, a cellular structure, a metallic 
ring, contain practically no impurities, and be capable 
of bearing a heavy burden in the furnace. 

The analysis of Connellsville coke with the coal 
from which it is prepared is given below. 

Water. Volatile Matter. Carbon. 
Coal 1.26 30.1 59.62 

Coke 0.03 1.29 89.15 

The Minor Solid Fuels. 

Sawdust and Spent Tan-bark find occasional use, 
their value depending upon the quantity of moisture 
they contain. With 57 per cent of moisture 1 pound 
of tan-bark gave an evaporation of 4 pounds of water. 

Wheat Straw finds application as fuel in agricul- 
tural districts, 3! pounds being equal to 1 pound of 
coal. Upon sugar-plantations the crushed cane or 
Bagasse, partially dried, is extensively used as a 



Sulphur. 


Ash. 


O.78 


8.23 


O.084 


9-52 



FUELS—SOLID, LIQUID, AND GASEOUS. A7 

fuel. With 16 per cent of moisture an evaporation 
of 2 pounds of water per pound of fuel has been 
obtained. 

b. Liquid Fuels. 

These consist of petroleum and its products, and 
various tarry residues from processes of distillation, 
as from petroleum, coking-ovens, wood and shale. 
Liquid fuel possesses the advantage that it is easily 
manipulated, and the fire is of very equable tempera- 
ture, very hot, and practically free from smoke. 

Regarding the origin of petroleum, many theories 
have been proposed. That of Engler,* that it was 
formed by the distillation under pressure of animal fats 
and oils, the nitrogenous portions of the animals pre- 
viously escaping as amines, seems most probable; it 
has yielded the best results of any hypothesis when 
tested upon an industrial scale. 

Crude Petroleum varies greatly in color according 
to the locality; it is usually yellowish, greenish, or 
reddish brown, of benzine-like odor, and sp. gr. of 0.78 
to 0.80. It " flashes " at the ordinary temperature; 
hence great care should be employed in its use and 
storage. Iks percentage composition is shown below. 

Carbon. Hydrogen. 

84.O-85.O 16. 0-15.O 

It is more than twice as efficient as the best anthra- 
cite coal. In practice 16 pounds of water per pound 
of petroleum have been evaporated, and an efficiency 
of 20,200 C. was obtained as against 8603 C. for 
anthracite. 

* Jour. Soc. Chem. Industry, 14, 648. 



48 GAS AND FUEL ANALYSIS. 

c Gaseous Fuels. 

Natural Gas is usually obtained when boring for 
petroleum and consists mainly of methane and hydro- 
gen, although the percentage varies with the locality. 
The Findlay, Ohio,* gas is of the following composi- 
tion: 



CH 4 


H 


N 


O 


C 2 H 4 


co 2 


CO 


H 2 S 


Sp. Gr, 


92.6 


2-3 


3.5 


0.3 


0.3 


0.3 


0.5 


0.2 


0.57 



Blast-furnace, Producer, or Generator Gas is the 

waste gas issuing from the top of a blast-furnace or 
obtained by partially burning coal by a current of air 
in a special furnace — a gas-producer or generator. It 
is mainly carbonic oxide and nitrogen. 

CH 4 Sp. Gr. 



CO 


N 


CO, 


H 


Blast-furnace gas 34.3 


63.7 


0.6 


1.4 


Producer gas 23.5 


65. 


1-5 


6.0 



3.0 1.0 

Fischer f states that 1 kg. coal gives 4.5 cu. m. gas 
of 4760 C, the coal giving 7950 C. or about 60 per 
cent of the value of the coal. This is calculated on 
the heating effect of the cold gas; if it were used hot 
as it leaves the producer, at about 690 C, the heating 
effect would be increased by 850 C. 

Water-gas. — If, instead of passing simply air over 
hot coal, water-vapor be employed, it is decomposed, 
giving carbonic oxide and hydrogen, according to the 
equation H,0 -\- C = CO -\- H 2 , and the resulting 
mixture is called water-gas. Its percentage composition 
is as follows: 

CO H CH 4 C0 2 N O Sp. Gr. 

45.8 45.7 2.0 4.0 2.0 0.5 0.57 

__ — — — — . — . . 

* Orton, Geology of Ohio, vol. vi. p. 137. 
\ Wagner's Chemical Technology. 



FUELS— SOLID, LIQUID, AND GASEOUS. 49 

Fischer* states that I kg. coal gives about 1.2 cu. 
m. gas, or about 58 per cent of the heating value. 

Coal or Illuminating Gas was formerly produced 
by the distillation of bituminous coal; it is at present 
largely made by the enriching of water-gas. " Gas- 
oil," a crude naphtha, is blown into the water-gas 
generator and changed to a permanent gas by the 
heat. Coal-gas is of the following composition: 



H 


CH 4 


CO 


C 2 H 4 


co 2 


N 


O 


Sp. Gr. 


.7.0 


40.5 


6.0 


4.0 


0.5 


1-5 


0.5 


0.4 



I kilo of coal gives about 0.3 cubic meter of gas, or 
about 20 per cent of the heating value. 

Heating Value of these Gases. 

Prof. Orton f gives the following relative values of 
the various gases. Omitting in all cases losses by 
radiation and assuming that the gases escape at 500 
F. and are burned with 20 per cent excess of air, 
1000 cu. ft. of each gas would evaporate from 6o° F. 
to 212 F. the following quantities of water expressed 
in pounds: 

Natural gas 893 

Coal " 591 

Water " 262 

Producer " 115 

Natural gas requires for its combustion about 
eleven times its volume of air, allowing for 20 per 
cent excess. 



* Taschenbuch fur Feuerungs Techniker, p. 27. 
f Ohio Geology, vol. vi. p. 544. 



CHAPTER VII. 

METHODS OF ANALYSIS AND DETERMINATION 
OF THE HEATING VALUE OF FUEL. 

SAMPLING. 

A FEW representative lumps or shovelfuls are taken 
from each barrow or from various points in the pile, 
roughly pulverized, and the whole spread out in a low 
circular heap. Diameters are drawn at right angles in 
it and opposite quarters taken, and treated similarly to 
the whole sample. The operation is continued until a 
sample of a few pounds is obtained. This is roughly 
crushed and samples taken at different points for the 
moisture determination; it is then further quartered 
down until a sample of 200 grams which passes a 
6o-mesh sieve is obtained. 

The methods employed in the analysis of fuels are 
largely a matter of convention, various methods giving 
varied results; for example, it is well-nigh impossible 
to obtain accurately the percentage of moisture in 
coal, as when heated sufficiently hot to expel the 
water some of the hydrocarbons are volatilized. 

Moisture. — Dry from i to 2 grams of the sample in 
a watch-glass exactly one hour at 105 to 1 io° C* 

Coke and Volatile Matter. — Carry about one gram 
of the sample, weighed into a platinum crucible, to 

* See an article by Hale, Proc. Am. Soc. Mech. Eng. 1896. 

50 



FUEL ANALYSIS— HEATING VALUE. 5 1 

the blast-lamp table; heat for exactly three and one 
half minutes by the watch in the hottest part of the 
Bunsen flame, it being from 7 to 8 inches long, and 
then for exactly three and one half minutes by the 
blast-lamp. The residue is coke. With anthracite 
coals the heating over the Bunsen burner is omitted. 

Carbon and Hydrogen. — These are determined by 
burning the coal in a stream of air and finally in 
oxygen, the products of combustion, carbon dioxide 
and water, being absorbed in potassium hydrate and 
calcium chloride. 

Apparatus Required. — Combustion-furnace similar 
to that shown in Fig. 13. Combustion-tube filled. 




Fig. 13. — Combustion-Furnace. 

Potash-bulbs with straight chloride of calcium tube 
filled. Chloride of calcium tube filled. Oxygen- 
holder, drying and purifying apparatus. Porcelain 
boat, desiccator, tongs, -J-inch rubber tubing. Ana- 
lytical balance. 

The combustion-tube is of hard glass, \ inch in in- 



52 GAS AND FUEL ANALYSIS. 

ternal diameter and 36 inches long, closed with per- 
forated rubber stoppers. One end — called the front 
end — is filled with a layer of copper oxide 12 inches 
long, held in place by plugs of asbestos coming 
within 4 inches of the stopper. In coals rich in sul- 
phur the oxide is partially replaced by a layer of 
chromate of lead 2 inches long. The position of the 
boat containing the coal is immediately behind this 
copper oxide; behind the boat is placed an oxidized 
copper gauze roll, 6 inches long. Before making the 
combustion, the tube and contents should be heated 
to a dull red heat in a stream of oxygen freed from 
moisture and carbon dioxide by the purifying appa- 
ratus, to burn any dust and dry the contents; it is 
then ready for use. 

The potash-bulbs are an aggregation of five bulbs, 
the three lowest filled with potassium hydrate of 1.27 
sp. gr., the other two serving as safety-bulbs, pre- 
venting the liquid from being carried over into the 
connectors. They should be connected further with a 
chloride of calcium tube to absorb any moisture carried 
away by the dry gas. When not in use they should 
be closed with connectors carrying glass plugs. Before 
weighing they should stand at least fifteen minutes in 
the balance-room to attain its temperature ; the weight 
should be to milligrams and without the connectors. 

The chloride of calcium tube is of U form, provided 
with bulbs for the condensation of the water; the 
granular calcium chloride is kept in place by cotton 
plugs, and the stopper neatly sealed in with sealing- 
wax. As calcium chloride may contain oxide which 
would absorb the carbon dioxide formed, a current o fe 



FUEL ANALYSIS— HEATING VALUE. 53 

dry carbon dioxide should be passed through the tube 
and thoroughly swept out by dry air before use. 

The chloride of calcium tube like the potash-bulbs 
should be placed in the balance-room fifteen minutes 
before weighing and, if the balance-case be dry, may 
be weighed without the connectors. It should be 
weighed to milligrams. 

The oxygen-holder may be like the Muencke aspi- 
rator, Fig. 12. The oxygen should be purified by 
passing through potassium hydrate and over calcium 
chloride. 

Operation, — The front stopper of the combustion- 
tube is slipped carefully upon the stem of the chloride 
of calcium tube and this connected to the potash- 
bulbs; 02 to 0.3 gram of the coal is carefully 
weighed into the porcelain boat (to o. 1 mg.), the roll 
removed, and the boat inserted behind the layer of 
copper oxide, and the roll and stopper replaced. 
The tube is now ready to be heated. 

The front of the copper oxide is first heated, the 
heat being gradually extended back; at this time the 
rear end of the copper roll is heated and a slow cur- 
rent of purified air passed through. This method 
of gradual heating of the tube is followed until the 
layer of copper oxide and the rear portion of the roll 
are at a dull red heat. Heat is now cautiously applied 
to the coal and the current of air slackened. The 
volatile matter in the coal distils off, is carried into 
the layer of copper oxide and burned; the carbon 
dioxide formed can be seen to be absorbed by the 
potassium hydrate. When this absorption almost 
ceases, oxygen is turned on and the coal heated until 



54 GAS AND FUEL ANALYSIS. 

it glows. The stream of oxygen should be so regulated 
as to produce but two bubbles of carbon dioxide in 
the bulbs per second. If the evolution be faster, the 
gas is not absorbed. When the coal has ceased glow- 
ing, oxygen is allowed to pass through the apparatus 
until a spark held at the exit of the last chloride of 
calcium tube (on the bulbs) re-inflames; the oxygen is 
allowed to run for fifteen minutes longer. The current 
of oxygen is now replaced by purified air, and the 
heat moderated by turning down the burners and 
opening the fire-clay tiles; the air is allowed to run 
through for twenty minutes to thoroughly sweep out 
all traces of carbon dioxide and moisture. The bulbs 
and U tube are disconnected, stopped up, allowed to 
stand in the balance-room, and weighed as before. 
The increase in weight in the bulbs represents the 
carbon dioxide formed; this multiplied by the factor 
0.2727 gives the carbon. Similarly the increase in the 
U tube, minus the water due to the moisture in the 
coal, represents the water formed, one ninth of which 
is hydrogen. 

Notes, — At no time in the combustion should any 
water appear near the copper roll, as it is an indication 
that the products of combustion have gone backward 
into the purifying apparatus and hence are lost. Such 
analyses should be repeated. Should moisture appear 
in the front end, it may be gently heated to expel it. 
Both ends of the tube should be frequently touched 
with the hand during the combustion, and should be 
no hotter than may be comfortably borne, as the 
stoppers give off absorbable gases when highly heated. 
Care should be taken not to heat the tube too hot, 



FUEL ANALYSIS— HEATING VALUE. 55 

fusing the copper oxide into and spoiling it. One 
tube should serve for a dozen determinations. It 
should not be placed upon the iron trough of the 
furnace, but upon asbestos-paper in the trough, to 
prevent fusion to the latter. 

As will be seen, the execution of a combustion is 
not easy, and should only be intrusted to an experi- 
enced chemist. The results obtained are usually o. I 
per cent too low for carbon and a similar amount too 
high for hydrogen. 

Ash. — This is determined by weighing the residue 
left in the boat after combustion, or by completely 
burning one gram of the coal contained in a platinum 
dish; often a stream of oxygen is used. 

Nitrogen is determined by Kjeldahl's method, 
which consists in digesting the coal with strong sul- 
phuric acid, aided by potassium permanganate, until 
nearly colorless. The nitrogenous bodies are changed 
to ammonia, which forms ammonium sulphate and 
may be determined by rendering alkaline and distil- 
ling the solution. 

Sulphur is determined by Eschka's method, con- 
sisting in heating for an hour one gram of the coal 
mixed with one gram of magnesium oxide and 0.5 
grm. sodium carbonate in a platinum dish without stir- 
ring, using an alcohol-lamp, as gas contains sulphur. 
It is allowed to cool and rubbed up with one gram of 
ammonium nitrate and heated for 5 to 10 minutes 
longer. The resulting mass is dissolved in 200 cc. of 
water evaporated to 150 cc, acidified with hydro- 
chloric acid, filtered, and sulphuric acid determined in 
the filtrate in the usual way wifrh barium chloride. 



56 GAS AND FUEL ANALYSIS. 

Oxygen is determined by difference, there being 
no direct method known. 

The analysis of gaseous fuels is conducted upon the 
same principles as indicated in Chapter II, Hempel's 
apparatus being employed, for the use of which refer- 
ence may be had to the author's " Handbook of Gas 
Analysis." 

DETERMINATION OF CALORIFIC POWER OF SOLID 
AND LIQUID FUEL. 

a. Direct Methods, 

Many forms of apparatus have been proposed for 
this purpose; few, however, with the exception of 
those employing Berthelot's principle — of burning 
the substance under a high pressure of oxygen — have 
yielded satisfactory results. The apparatus of William 
Thomson,* and also that of Barrus, in which the coal 
is burnt in a bell-jar of oxygen, yield results varying 
as much as 8 per cent from the calculated value. f 
It is further inapplicable to semi-bituminous and an- 
thracite coals, as the ash formed over the surface pre- 
vents the combustion of the coal beneath it. 

Fischer's calorimeter \ is similar in principle, but is 
claimed to give very good results. § 

Lewis Thompson's calorimeter, in which the coal is 
burnt in a bell-jar by the aid of oxygen furnished by 
the decomposition of potassium chlorate or nitrate, is 

* Thomson, Jour. Soc. Chemical Industry, 5, 581. 
f Ibid., 8, 525. 

% Zeit. f. angewandte Chemie, 12, 351. 

§ Bunte, Jour. f. Gasbeleuchtung und Wasserversorgung, 34, 
21, 41. 



FUEL ANALYSIS— HEATING VALUE. $7 

open to several objections, the chief of which are: I. 
The evolution of heat due to the decomposition of the 
oxidizing substance used. 2. Loss of heat due to 
moisture carried off by the gases in bubbling through 
the water. The results which it gives must be in- 
creased by 15 per cent.* 

Hempel's apparatus f makes use of the Berthelot 
principle: the coal must be compressed into a cylinder 
for combustion — a process to which every coal is not 
adapted — only applicable to certain varieties of 
bituminous and brown coal. The mixture with the 
coal of any cementing or inflammable substance to 
form these cylinders carries with it the necessity of 
accurately determining its calorific power beforehand. 

The best apparatus for the purpose is probably that 
of Mahler,;}; modified by Holman and Williams, the 
modifications consisting in replacing the enamel lining 
by electroplating the inside with gold and in improved 
methods of making the apparatus tight. 

The Mahler apparatus, Fig. 15, consists of a mild- 
steel cylinder B } with w^alls half an inch thick, narrowed 
at the top for connection by a screw-joint with the 
cover carrying the vessel C to contain the coal. This 
cylinder or bomb is placed inside the calorimeter D, 
and this inside a jacket A. At the right is shown a 
portion of the oxygen-cylinder and the gauge. 

For the following directions for its use the author 
is indebted to the kindness of Professor Silas W. 
Holman of the Institute of Technology. 

* Scheurer-Kestner Jour. Soc. Chemical Industry, 7, 869. 
f Hempel, " Gasanalytische Methoden," p. 347. 
% Mahler, Jour. Soc. Chemical Industry, 11. 840. 



^8 



GAS AND FUEL ANALYSIS. 



Preparation of Bomb. — Remove the ring upon 
which it sits in the calorimeter. 

Wash out the bomb. It need not be dry. Leave 
cover off. 

See that the lead-ring washer P y Fig. 14, is in good 
condition. Unless its upper surface 
is fairly smooth the cover cannot be 
tightly closed. Repeated screwing 
on of the cover raises a burr of lead. 
When this becomes noticeable it must 
be removed by cutting with a knife- 
blade. If there is difficulty in mak- 
ing the cover tight, it is most likely 
to be due to this cause. 

Grease the screw 5 upon the out- 
side of the bomb slightly with tallow 
or a heavy oil, but be sure that none 
of the grease gets beyond the lead 
washer. 

Fig. 14.— Mahler's Secure the bomb very firmly in the 
Bomb. heavy clamp on the table. 

Place the top on a ring or in a clamp of a lamp-stand 
and in an upright position. 

Put in position the platinum tray C and the rod E, 
Fig. 15. 

Twist on the loop of ignition-wire (fine platinum 
or iron). This must make good electrical contact 
with both E and the pan or its supporting rod. 
Failing this the current will not flow to fuse the wire. 
Failure to ignite is almost always traceable to this 
cause. 

Pour into the tray a known weight of the substance 




FUEL ANALYSIS— HEATING VALUE. 



59 



to be burned. If this be coal, slightly over one gram 
should be used. It is usually best inserted from a 
small test-tube weighed before and after, with due 
precautions against loss. 

The ignition-wire should dip well into the coal. 

The fineness required in the combustible depends 




Fig. 15. — Mahler's Apparatus Complete. 

upon its nature. Anthracite coal should be in a very 
fine powder. Trial will show whether any unburned 
grains remain, indicating that the combustible is too 
coarse. 

The standard which carries the pressure-gauge 
should be screwed to the table near the bomb-clamp, 
and the oxygen cylinder must be placed near by so 
that the three may be easily connected by the flexible 
copper tube. 



60 GAS AND FUEL ANALYSIS. 

The top carrying the charge is then cautiously (to 
avoid loss of charge by jarring or draft) transferred to 
the bomb and screwed carefully home. The lifting is 
best done by hooking the fingers beneath the milled 
head at the top of the valve-screw R. The top must 
be set up hard by the wrench which takes the large 
nut cut on the cover. In setting this up it is desirable 
to use no more force than is necessary to secure a gas- 
tight bearing of the tongue of the cover against the 
lead washer P. Just the force required can only be 
learned by experience, but it is always considerable. 
A slight leak is unimportant, but it is not difficult to 
secure a tight seal if the lead washer be kept in good 
condition. 

To fill with oxygen proceed as follows: 

Screw down the valve-screw R gently to close the 
valve. Connect the copper tube to the oxygen-tank 
gauge, and to the bomb at N. See that there are 
leather washers at the joints. Turn the connecting 
nuts firmly but not violently home. The connections 
to the oxygen-tank and gauge are usually left undis- 
turbed, and only that at N has to be made each time. 

It is now necessary to test for leakage in the con- 
nections. To do this, as R is closed, it is only neces- 
sary to open the oxygen-tank cautiously by means of 
its wrench until the gauge indicates 5 or 10 atmos- 
pheres and then close it. As the tank when freshly 
charged has a pressure of 120 atmospheres, and the 
gauge reads only to 35 atmospheres, care must be used 
in all manipulations not to overstrain the gauge, also 
avoid suddenly releasing the pressure on the gauge. 
When this pressure is on, any leak in the connections 



FUEL ANALYSIS— HEATING I'ALUE. 6 1 

will be indicated by a drop in the gauge reading. If 
a leak exists, it must be removed or rendered extremely- 
slow before proceeding further. It is most likely to 
be found in the joints, which must be tightened one 
by one until the leak stops. 

Now to fill the bomb it is next necessary to open 
R. This could be done by merely turning back the 
milled head, or the nut just above it. But as this 
would put a twist into the copper connecting-tube 
(which many times repeated would break it), the better 
way is, holding one wrench in each hand, to loosen 
the connecting nut above N by a half-turn, holding R 
by the wrench and nut, then to turn the nut open 
a half-turn or until it is again tight in. This leaves 
the connections tight and R open into the bomb. The 
oxygen is then turned slowly on, and the bomb 
gradually fills. If a gram of coal is to be burned, a 
pressure of 25 atmospheres gives the proper amount of 
gas in the bomb. Note that the valve R and the inlet- 
tube have small borings. Thus the inflow of gas will 
be slow and the pressure in the connecting-tube will 
be higher than in the bomb. If, therefore, the tank 
be closed quickly, the gauge-reading will fall somewhat 
until these pressures equalize, and will then remain 
stationary unless there is a leak. The tank-cock must 
always be kept well under control to avoid overcharg- 
ing either gauge or bomb. 

When the bomb is full, close first the tank-cock. 
Then, to close R f put the wrenches on the nuts and, 
holding one from turning, set the other down until R 
is tight, but not too tight. Avoid straining R, which 
closes tight very easily. By this method the copper 



62 GAS AND FUEL ANALYSIS. 

tube is not twisted. There is of course a slight leak 
of gas from the bomb after TV leaves the nut and 
before R is closed, but the time required for the half- 
turn is so short and the outflow so slow that the loss 
is insignificant. There is no need to hurry in this 
operation. Be deliberate and careful of the apparatus. 
■A valve like R is a nice piece of workmanship, and to 
endure much usage it must be treated with care. 

The bomb is now ready to be undamped and set 
into the ring preparatory to transfer to the calorimeter. 
It can be left standing indefinitely, but must be 
handled with caution (best by lifting with fingers 
beneath R, to avoid spilling the charge). 

Preparation of Calorimeter. — The outer jacket of 
the calorimeter should be filled with water at about 
the room temperature or a few degrees higher. If 
left standing from day to day it will usually be nearly 
enough right. It is well to stir it (blow air through 
it) somewhat before beginning work, if it has stood for 
some time. 

Be sure that the inner surface of this jacket, i.e., 
the one which is next the calorimeter, is thoroughly 
dry, and do not let any water spill into it — or remove 
it if it does so. 

Thoroughly dry the outer surface of the calorimeter 
and keep it so. Moisture depositing on or evaporating 
from the surface of the calorimeter is sure to cause an 
irregular error which may spoil otherwise good work. 

Put the calorimeter in place. Transfer the bomb to 
it, and adjust the stirrer so that it works properly. 

Pour in the proper amount of water, about 2.25 



FUEL ANALYSIS— HEATING VALUE. 63 

liters, at a suitable temperature, best by using marked 
flasks carefully calibrated beforehand. 

Insert the thermometer. 

See that the electrical attachments are ready for 
instantaneous use. The whole is then ready for the 
combustion. 

Combustion Observations. — With apparatus all in 
place run the stirrer briskly and continuously until 
the completion of the work. Allow about five minutes 
for everything to come to a normal condition. Then 
take temperature readings to at least 0.01 at each 
quarter minute for at least five minutes. Record the 
times (h. m. s.) and corresponding thermometer-read- 
ings, thus: 



Time. 


Temp. 


Remarks. 


2 h I5 m O s 


15°. 24 


After 5 m stirring 


15 


.24 




30 


.25 




45 


•25 




16 


.25 




15 


.26 




30 


.26 




25 


— 


Coal ignited 


15 


15.6 




30 


•9 




45 


16.2 




26 


•5 




etc. 


etc. 





Exactly at the beginning of a noted minute close 
the electric circuit through the fuse-wire. If the 
arrangements are right, this will cause the coal to 
ignite at once and the combustion is almost instan- 
taneous. Owing to the time required to transmit the 



64 GAS AND FUEL ANALYSIS. 

heat through the bomb to the water, the temperature, 
however, will continue to rise for two or three minutes. 
Keep up the steady stirring and the quarter-minute 
temperature-readings for at least ten minutes after 
ignition, recording as above. One or two observations 
maybe unavoidably lost before and after ignition, but 
this does not materially affect the results. The read- 
ings during the rapid rise are also less close. 

As soon as the rise begins to slow down, however, 
the hundredths of a degree must again be secured. 
This makes a series of observations of 15 to 20 
minutes' duration. The use of the readings to obtain 
the cooling correction and the corrected rise of tem- 
perature of the calorimeter is given under the heading 
" Cooling Correction ' * farther on. 

This completes the observations unless it is desired 
to test the character of the products of combustion. 
The bomb should now be opened and rinsed, as the 
nitric acid formed by the oxidation of the nitrogen in 
the coal and air attacks the metallic lining unless it be 
of gold. Also the top is more easily unscrewed at 
first than later, Leave the top off. 

Before unscrewing the top of the bomb be sure to 
open the valve R to relieve the presure. 

Heat Capacity of Bomb and Calorimeter. — The 
heat capacity of the bomb may be found: 

1. From the weights and assumed specific heats of 
the parts. 

2. By raising the bomb to an observed high tem- 
perature and immersing in water, i.e., by the usual 
" method of mixtures." 

3. By burning in it a substance of known heat of 



FUEL ANALYSIS— HEATING VALUE. 65 

combustion, such as pure naphthaline, and calculating 
back to find the heat capacity of the bomb. 

The first method is not reliable. Errors of several 
per cent may enter in the assumed specific heats. 

The second method is very difficult of exact per- 
formance, owing to the size and form of the bomb. 

The third method is by far the most reliable, but of 
course depends on the correctness of the assumed heat 
of combustion of the substance used. That of naphtha- 
line has been so well determined by Bertheiot and 
others,"* and the substance is so easily and cheaply 
obtained in a pure state, that dependence can be 
placed on the results. This method has the great 
advantage that it involves the use of the apparatus in 
precisely the same way as in subsequent determina- 
tion, so that any systematic errors of method tend to 
cancel one another. It also determines at the same 
time the heat capacity of the calorimeter and stirrer 
just as used. 

The capacity of the calorimeter and stirrer may 
best be determined in connection with that of the 
bomb by the third method just described. Otherwise 
it may be found by the first method, or by a method 
similar to the second, viz., by pouring into the calorim- 
eter when partly full water of a known temperature 
different from that of the water in the calorimeter, 
noting all temperatures and weights, This last 
method, however, is very unsatisfactory in practice 
owing to the small heat capacity of the calorimeter 
and to the losses of heat in pouring the water, etc. 

* 1 gram of naphthaline evolves 9692 C. This is the average of 
150 determinations by four different obervers. 



66 GAS AND FUEL ANALYSIS. 

A general expression for computing the heat of 
combustion from the bomb observations is as follows: 
Let n represent the number of grams of combustible, 
H the heat of combustion sought, W the weight of 
water in the calorimeter, and k the heat capacity, 
or water equivalent, of bomb, calorimeter, stirrer, 
thermometer, etc. ; t x and / 2 represent the initial and 
final temperatures of the water. Then 

whence 

H= 1 -{WJ r k){t i -t 1 ). 

This expression is exact if t t2 is corrected for loss by 
cooling as described in the methods for 4i Cooling 
Correction/ ' p. 6j. 

The value of k may be determined by either of the 
following methods; a simplification may, however, be 
introduced which will save much labor if an accuracy 
of not more than about one per cent is sought, pro- 
vided that k is found by burning naphthaline or other 
known substance. Use enough of this substance to 
cause about the same rise, / 2 — /, , (within i°) as will be 
caused by one gram of coal. Omit the cooling correc- 
tion entirely, using for / 2 the maximum temperature 
attained. Then compute k\ this value will be erro- 
neous by a small amount owing to the neglect of the 
correction. Now in subsequent measurements on coal 
also neglect the cooling correction, using for / 2 the 
maximum observed temperature as before, thus leav- 
ing an error in / 2 . Since the rise /„ — /, in both cases 
will be nearly the same, the error in k will almost 



FUEL ANALYSIS— HEATING VALUE. 67 

exactly affect that in t 2 in the coal-test, and the result- 
ing value of H will be nearly free from this error. 
This method of course implies that W is nearly con- 
stant and that t 1 is systematically arranged to be either 
about at the air-temperature or a definite amount 
below it, as described under " Cooling Correction/' 
so that the cooling loss is about the same. The time- 
interval from t 1 to t 2 must for the same reason be 
nearly constant in all cases. 

Cooling Correction. — In all careful calorimetric 
work, one of the most troublesome sources of error is 
the loss or gain of heat by the calorimeter from its 
surroundings. This loss or gain is due to radiation, 
to air-convection currents, and to evaporation or con- 
densation. Unavoidable irregularities in the condi- 
tions and the smallness of the quantities to be measured 
render the amount of the correction variable and its 
determination uncertain. Many methods of making 
the correction have been proposed. One of the best 
of these is the first of the two given below, but the 
second, although a little more troublesome in the 
execution of the work, appears to be more trustworthy 
in its results. The second method is to be used. 

First Method. — This is described in the Physical 
Laboratory Notes, I,* under " Specific Heat of Solids." 
In this method the water at the outset should be at 
such a temperature that it is gaining very slowly. 
For an open calorimeter this is about i° or 2° below 
the air-temperature, but varies with circumstances. 
Water which has been long standing in the room is 
generally about right. 

Second Method. — For the discussion and details 

^Obtainable from C. E. Ridler, Bookseller, Boston. 



68 CAS AND FUEL ANALYSIS. 

reference may be had to an article by Professor 
Holman in Proc. American Academy of Arts and 
Sciences, 1895, p. 245; also in The Technology 
Quarterly, 8, 344. 

Berthiers Method. — Another method of direct 
determination was proposed by Berthier in 1835.* 
It uses as a measure of the heating value the amount 
of lead which a fuel would reduce from the oxide; in 
other words, it is proportional to the amount of oxygen 
absorbed. 

The method is as follows: Mix one gram of the fine 
dry coal with from 20 to 40 grams of oxychloride and 
oxide of lead, cover with 20 grams of oxide of lead 
(litharge), heat to redness in a crucible, and weigh the 
lead button formed. One part of carbon is theoretically 
equivalent to 34 parts of lead (or 235 f calories) (C). 

While this method of course can make no preten- 
sions to scientific accuracy, yet the results seem as 
trustworthy as those obtained by calculation accord- 
ing to Dulong's formula (see b, below), and it is readily 
applicable. 

b. Determination of Heating Value by Calculation. 

The method of determination of the heating value 
first described, though exact, has the disadvantages 
that the apparatus is costly and the compressed 
oxygen is not easily obtained. To obviate these, 
it has been sought to obtain the heating value by 
calculation from the chemical analysis, the heating 
value of the constituents being known. This has 
the disadvantage that we have no absolute knowl- 

* Dingler's Polytechnisches Journal, 58, 39L 

f Prof. W. A. Noyes finds this factor much too low in practice, and 
employs 268 or even 300. 



FUEL ANALYSIS— HEATING VALUE. 69 

edge — nay, not even an approximate idea — as to how 
the carbon, hydrogen, water, and sulphur exist in the 
coal, so that any formula must of necessity be quite 
removed from the truth. Dulong was the first to 
propose the method by calculation, and his formula* is 



H 



100 



c y h, and representing the percentages of carbon, 
hydrogen, and oxygen in the coal. 

Many modifications of this, considering the water 
formed, the heat of vaporization of carbon, or the 
volatile hydrocarbons, have been proposed. 

Bunte f finds that the following formula \ gives results 
varying from -f- 2.8 to — 3.7 per cent: 

8080^-f- 28800 \h — o ) + 2500^ — 6oow 

100 

s and w represent the percentages of sulphur and 
water respectively. It is, however, inapplicable to 
anthracite coal. It would scarcely seem that the 
sulphur would be worth considering unless high, one 
per cent affecting the result but 0.3 per cent. 
Mahler employs the formula* 

8140^ -f- 34500^ — 3000(0 -f- n) 
100 ' 

o and n representing oxygen and nitrogen, and states 
that it gives results within 3 per cent. 

The results obtained by these formulae for anthracite 
coal are as a rule considerably too low. 

* H burned to liquid water. \W burned to aqueous vapor, 

f Jour, fur Gasbeleuchtung, 34, 21-26 and 41-47. 



70 GAS AND FUEL ANALYSIS. 

CALORIFIC POWER OF GASEOUS FUEL. 

a. Direct Determination. 
Perhaps the best apparatus for the determination of 
the heating value of gases is the Junker calorimeter, 
Figs. 16 and 17. The following description is taken 




Fig. 16. — Junker Gas Calorimeter (Section). 

from an article by Kuhne in the Journal of the Society 
of Chemical Industry, vol. 14, p. 631. As will be 



FUEL ANALYSIS— HEATING VALUE. 



n 



seen from Fig. 16, this consists of a combustion-cham- 
ber, 28, surrounded by a water-jacket, 15 and 16, 
this being traversed by a great many tubes. To 
prevent loss by radiation this water-jacket is sur- 




Fig. 17.— Junker Gas Calorimeter. 

rounded by a closed annular airspace, 13, in which 
the air cannot circulate. The whole apparatus is 
constructed of copper as thin as is compatible with 
strength. The water enters the jacket at 1, passes 
down through 3, 6, and 7, and leaves it at 21, while 



7 2 GAS AND FUEL ANALYSIS. 

the hot combustion-gases enter at 30 and pass down, 
leaving at 31. There is therefore not only a very 
large surface of thin copper between the gases and the 
water, but the two move in opposite directions, during 
which process all the heat generated by the flame is 
transferred to the water, and the waste gases leave the 
apparatus approximately at atmospheric temperature. 
The gas to be burned is first passed through a meter, 
Fig. 17, and then, to insure constant pressure, through 
a pressure-regulator. The source of heat in relation 
to the unit of heat is thus rendered stationary; and in 
order to make the absorbing quantity of heat also 
stationary, two overflows are provided at the calo- 
rimeter, making the head of water and overflow con- 
stant. The temperatures of the water entering and 
leaving the apparatus can be read by 12 and 43; as 
shown before, the quantites of heat and water passed 
through the apparatus are constant. As soon as the 
flame is lighted, 43 will rise to a certain point and will 
remain nearly constant. 

Manipulation. — The calorimeter is placed as shown 
in Fig. 17, so that one operator can simultaneously 
observe the two thermometers of the entering and 
escaping water, the index of the gas-meter, and the 
measuring-glasses. 

No draft of air must be permitted to strike the ex- 
haust of the spent gas. 

The water-supply tube w is connected with the 
nipple a in the centre of the upper container; the 
other nipple, b, is provided with a waste-tube to carry 
away the overflow, which latter must be kept running 
while the readings are taken. 



FUEL ANALYSIS— HEATING VALUE. 73 

The nipple c through which the heated water leaves 
the calorimeter is connected by a rubber tube with 
the large graduate, d empties the condensed water 
into the small graduate. 

The thermometers being held in position by rubber 
stoppers and the water turned on by e until it dis- 
charges at c, no water must issue from d or from 39, 
Fig. 16, as this would indicate a leak in the calorim- 
eter. 

The cock e is now set to allow about two liters of 
water to pass in a minute and a half, and the gas 
issuing from the burner ignited. Sufficient time is 
allowed until the temperature of the inlet-water 
becomes constant and the outlet approximately so; 
the temperature of the inlet-water is noted, the read- 
ing of the gas-meter taken, and at this same time the 
outlet-tube changed from the funnel to the graduate. 
Ten successive readings of the outflowing water are 
taken while the graduate (2-liter) is being filled and 
the gas shut off. 

Example. — Temp, of incoming water, 17. 2° 

" outgoing " 43. 8° 
Increase, 26. 6° 

Gas burned, 0.35 cu. ft. 
liters water X increase of temp. 2 X 26.6 



Heat 



cu. ft. gas 0.35 

= 152.3C. 



From burning one cubic foot of gas 27.25 cc. of 
water were condensed. This gives off on an average 
0.6 C. per cc. 



74 GAS AND FUEL ANALYSIS. 

27.25 X 0.6 = 16.3C; 
152.3 — 16.3 = 136 C per cubic foot; 
136 X 3.96828 = 540B.T.U. 

The apparatus has been tested for three months 
in the German Physical Technical Institute with hy- 
drogen, with but a deviation of 0.3 per cent from 
Thomson's value. This value may vary nearly that 
amount from the real value owing to the method 
which he employed. 

b. By Calculation. 

Oftentimes it may be impracticable to determine 
the heating value of gases directly; in such cases 
recourse must be had to the calculation of its calorific 
power from volumetric analysis of the gas. 

To this end multiply the percentage of each con- 
stituent by its number as given in Table IV, and the 
sum of the products will represent the British Thermal 
Units evolved by the combustion of one cubic foot of 
the gas.* It is assumed that the temperature of the 
gas burned and the air for combustion is 6o° F., and 
that of the escaping gases is 328 F., that correspond- 
ing to the temperature of steam at 100 pounds abso- 
lute pressure. 

As has been already stated, column 3 in Table IV 
is based upon the assumption that the gas, and air for 
its combustion, enter at 6o° F., and the products 
of combustion leave at 328 F. ; in column 4 it is 
assumed that the entering temperature of both gas 
and air is 32 F., and the combustion-gases are cooled 

* H. L. Payne, Jour. Analytical and Applied Chern., 7, 230. 



FUEL ANALYSIS— HEATING VALUE. 75 

to 32° F. In case these conditions are varied, the 
amount of heat which the gas and air bring in must be 
determined; this is found in the usual way by multi- 
plying the proportionate parts of 1 cubic foot, as 
shown by the analysis, by the specific heat of the gas, 
and this by the rise in temperature (difference between 
observed temperature and 32 F.). The quantity of 
air necessary for combustion is found by multiplying 
the percentage composition of the gas by the number 
of cubic feet necessary for the combustion of each 
constituent. 

An example will serve to make this clear. The 
analysis of Boston gas is as follows:* 

C0 2 lt Illuminants." O CO CH 4 H N 

2.9 15.O O.O 25.3 25.9 27.9 3.0 

Or in one cubic foot there are 

.029 C0 2 . 259 CH 4 

.150 " illuminants ,, 279 H 

.253 CO , 030 N 

Let us suppose its temperature is 62 F. The 
quantity of heat which one cubic foot of the gas brings 
in is then the sum of the heats of its constituents; 
this latter is its volume X volumetric specific heat X 
rise in temperature. 

The " volumetric " specific heat is the quantity of 
heat necessary to raise one cubic foot of the gas from 
32 to 33 F. ; these are given in the Appendix, 
Table II. 

* Jenkins, Annual Report Inspector of Gas Meters and Illumi- 
nating Gas, 1896, p. ii. 



76 GAS AND FUEL ANALYSIS. 

Vol. Vol. Sp. Ht. Rise. 

" Illuminants " = 0.15 X 0.04 X 0.30 = .18 B.T.U. 
CO = 0.253 X 0.019 X 0.30 = .14 

CH 4 = 0.259 X 0.027 X 0.30 = .21 

H = 0.279 X 0.019 X 0.30 = .16 

CO a N insignificant. 

Total heat brought in by gas 0.69 B.T.U. 

The quantity of air necessary to burn these several 
gases is, Table III: 

"Illuminants" 0.15 X 14.34=2.15 

CO 253 X 2.39= .60 

CH 4 259 X 9-56 = 2.48 

H 279 X 2.39= .67 

Theoretical quantity of air 5.90 cu. ft. 

Add 20 per cent excess 1.20 

Quantity of air used in burning 1 cubic 

foot of Boston gas , 7. 10 cu. ft. 

Assume its temperature to be 72 F. ; then the 
heat it brings in is 

7.1 X .019 X 0.40 = 5.4 B.T.U. 
Total gain is 5.4 -f- 0.7 = 6.1 B.T.U. 

Assume further that the gases, instead of passing 
out at a temperature of 328 F., leave at the same 
temperature as that of the chimney-gases, p. 29, 250 
C. or482° F. 

The calculation of the heat carried away is similar 
to that there given. 



FUEL ANALYSIS— HEATING VALUE, 77 

0.15 cu. ft. of " illuminants •' produces, Table III, 

0.3 cu. ft. C0 2 and 0.3 cu. ft. steam; 
0.253 cu. ft. of carbonic oxide produces .253 cu. ft. 

C0 2 ; 
0.259 cu. ft. methane produces 0.259 cu - ft- C0 2 and 

.518 cu ft. steam; 
0.279 cu. ft. hydrogen produces .279 cu. ft. steam. 

From the combustion of the gas there results .812 
cu. ft. C0 2 , 1.097 cu. ft. steam, and 5.90 X 79.08 or 
4.665 cu. ft. N. 

The a x uantity of heat they carry off is as follows: 

Vol. Vol. Sp. Ht. Rise. B.T.U. 

C0 2 812 X .027 X 45o= 9-9 

N 4.66 X .019 X 45o= 39-9 

Excess of air.. 1.2 X .019 X 450= 10.2 

Steam 1-097 X .0502 X 1229 = 67.7 

Total heat lost = 127.7 

The loss due to the steam is found by multiplying 
the weight of steam found by the " Total Heat of 
Steam," as found from Steam Tables.* The tables, 
however, do not extend beyond 428 F. ; it can be 
calculated by the formula 

Total heat = A = 1091.7 -f- 0.305(7 — 32). 

One cubic foot of hydrogen when burned yields 
.0502 lbs. of water. 

The heat generated by the combustion of the gas is 
found by multiplying its volume by its calorific power, 
Table IV. 

* Peabody's Steam Tables. 



78 GAS AND FUEL ANALYSIS. 

* l Illuminants" 0.15 X 2000.0 = 300.0 B.T.U 

CO 0.253 X 34i.2= 86.3 

CH 4 0.259 X 1065.4=276.0 

H 0.279 X 345-4= 96.3 



Heat generated by the gas. 758.6 B.T.U, 

Heat gained by rise in temperature 

of entering gas (62 F.) and air 6.1 

(72° F.) 

764.7 

Total heat lost 127.7 



637.0 B.T.U. 

This figure, 637 B.T.U., represents the heating 
power of one cubic foot of the gas measured at 62° F., 
and is consequently too large; its heating value at 
32 F. is represented by 

X 637, or 600.3 B.T.U. 



492 + 30 



APPENDIX. 



TABLE I. 

TABLE SHOWING THE TENSION OF AQUEOUS VAPOR AND ALSO THE 
WEIGHT IN GRAMS CONTAINED IN A CUBIC METER OF AIR 
WHEN SATURATED. 

o 



From 5 to 30 C. 



Temp. 


Tension, 


Grams. 


Temp. 


Tension, 


Grams. 


Temp. 


Tension, 


Grams. 




mm. 






mm. 






mm. 




5 


6-5 


6.8 


14 


II. 9 


12.0 


23 


20.9 


20.4 


6 


7.0 


7-3 


15 


12.7 


12.8 


24 


22.2 


21.5 


7 


7-5 


7-7 


16 


13-5 


13.6 


25 


23.6 


22.9 


8 


8.0 


8.1 


17 


14.4 


14.5 


26 


25.O 


24.2 


9 


8-5 


8.8 


18 


15.4 


15. 1 


27 


26.5 


25.6 


10 


9.1 


9.4 


19 


16.3 


16.2 


28 


28.I 


27.O 


11 


9.8 


10. 


20 


17.4 


17.2 


29 


29.8 


28.6 


12 


10.4 


10.6 


21 


18.5 


18.2 


30 


31-5 


29.2 


13 


11. 1 


n-3 


22 


19.7 


19.3 









TABLE II. 

VOLUMETRIC " SPECIFIC HEATS OF GASES.* 



Air 0.019 

Carbon dioxide 0.027 

Carbonic oxide 0.019 

Hydrogen 0.019 



" Illuminants " 0.040 

Methane 0.027 

Nitrogen 0.019 

Oxygen 0.019 



The "volumetric" specific heat is the quantity of heat neces- 
sary to raise the temperature of one cubic foot of gas from 32 F. 
to 33° F. 



* H. L. Payne, Jour. Anal, and Applied Chem., 7, 233. 

79 



8o 



APPENDIX, 



TABLE III. 

THE VOLUME OF OXYGEN AND AIR NECESSARY TO BURN ONE CUBIC 
FOOT OF CERTAIN GASES, TOGETHER WITH THE VOLUME OF 
THE PRODUCTS OF COMBUSTION. 



Name. 



Hydrogen 

Carbonic oxide. 

Methane 

Ethane 

Propane 

Butane 

Pentane 

Hexane 

Ethylenef 

Propylene^ 
Benzene^ 



Formula. 



H 2 

CO 

CH 4 

C 2 H 6 

C3H8 

C4H10 

C5H 1 2 

C6O14 

C2H4 

C3H6 

CfiHfi 



Volume of 


Volume* 


Oxygen. 


of Air. 


0.5 


2-39 


0.5 


2-39 


2.0 


9.56 


3-5 


16.73 


5-0 


23.90 


6.5 


3I-07 


8.0 


38.24 


9-5 


45-41 


3-o 


14-34 


4-5 


21.51 


7-5 


35-85 



Volume of 
Steam. 



Volume of 
Carbon 
Dioxide. 



* Air being 20.92 per cent by volume, 4.78 volumes contain 
1 volume of oxygen, 
f The chief constituent of " illuminants," new name "ethene." 
% New name " propene." 
§ Often called benzol, not to be confounded with benzene. 



TABLES. 
TABLE IV. 



81 



CALORIFIC POWER OF VARIOUS GASES* IN BRITISH THERMAL UNITS 

PER CUBIC FOOT. 



Name. 



Hydrogen 

Carbonic oxide 

Methane 

Illuminantsf. . . 

Ethane 

Propane. ....... 

Butane 

Pentane 

HexaneJ 

Ethylene 

Propylene 

Benzene 



Symbol. 



H 

CO 

CH 4 

C a H6 
C3H8 
C4H10 
C5H12 

CeHi4 
C2H4 
C3H6 
CeH6 



6o° initial. 
328 final. 



263.2 

306.9 

853.O 

1700.O 



32 initial. 
32 final. 



345.4 
341.2 
I065.O 
2000.0 
I86I.O 
2657.O 
344I.O 
4255.O 
50I7.0 
1674.O 
2509.O 
4OI2.O 



* H. L. Payne, loc. cit. 

f Where the " illuminants " are derived chiefly from the decom- 
position of mineral oil. 

% The chief constituent of the "gasolene" used in the gas 
machines for carburetting air. 



TABLE V. 

SHOWING THE WEIGHT OF A LITER AND SPECIFIC GRAVITY REFERRED 
TO AIR, OF CERTAIN GASES AT 0° C. AND 760 MM. 



Name of Gas. 



Carbonic oxide 
Carbon dioxide 

Hydrogen 

Methane 

Nitrogen 

Oxygen 

Air 



Weight, Grams. 


Spe( 


:ific Gravity. 


I-25I 




O.967 


I.966 




I. 519 


O.0896 




O.069 


O.715 




0.553 


1.255 




O.970 


I.430 




1. 105 


I.294 




I. OOO 



82 



APPENDIX. 



TABLE VI. 

SOLUBILITY OF VARIOUS GASES IN WATER. 

One volume of water at 20° C. absorbs the following volumes of 
gas reduced to o° C. and 760 mm. pressure. 



Name of Gas. 



Carbonic oxide 
Carbon dioxide 

Hydrogen 

Methane 

Nitrogen 

Oxygen 

Air 



Symbol. 


Volumes. 


CO 


O.023 


co 2 


O.901 


H 2 


O.019 


CH 4 


O.035 


N 2 


0.014 


o 2 


O.028 


.... 


0.017 



TABLE VII. 



MELTING-POINTS OF VARIOUS METALS AND SALTS, FOR USE WITH 

APPARATUS FIG. II. 

(From Carnelley Melting- and Boiling-point Tables.) 



Alphabetically. 

Aluminium 66o c 

Antimony 432 

f Barium chloride. .. . 860 

Bismuth 268 

fCalcium fluoride. .. . 902 

Cadmium 320 

f Cadmium chloride. . 541 

Copper 1095 

Lead 334 

f Potassium chloride.. 734 

fSodium chloride. .. . 772 

Tin 233 

Zinc 433 



By Temperatures. 

Tin 

Bismuth 

Cadmium 

Lead 

Antimony 

Zinc 

Cadmium chloride. . . . 

Aluminium 

Potassium chloride... 

Sodium chloride 

Barium chloride 

Calcium fluoride 

Copper 



233° C, 

268 

320 

334 

432 

433 

541 

660* 

734 
772 
860 
902 
1095* 



* Holman, Proc. Am. Academy, 31, 2t8. 

f These salts must be dried at 105 C. to constant weight. 



TABLES. 
TABLE VIII, 



83 



GIVING THE NUMBER OF TIMES THE THEORETICAL QUANTITY OF 
AIR SUPPLIED, WITH VARIOUS GAS ANALYSES.* 



co+o 


C0 2 +0+CO=2i 


N= 80. 
C0 2 4-0+CO= 20 . 


N = 81. 
C0 2 +OfCO=i9. 


N = 82. 
C0 2 +0+CO = i8. 


21 


1. 00 








20 


1.05 


1. 00 


.... 


.... 


19 


I.IO 


1.05 


I. OO 


.... 


18 


1. 17 


I.IO 


I.05 


1.00 


17 


I.23 


1. 16 


I.IO 


1.05 


16 


i-3i 


1.23 


1. 16 


I.IO 


15 


1.40 


1. 31 


1.23 


1. 16 


14 


1.50 


1-39 


1.30 


1.22 


13 

12 


1. 61 
1-75 


1.49 

1.60 


1-39 
1.48 


I.30 

1.38 


II 

IO 


1. 91 
2.10 


1-73 

1.89 


1.59 
1.72 


1.47 

1.58 


9 

8 


2.33 
2.62 


2.07 
2.29 


1.87 
2.04 


I.70 

I.85 


7 


3.00 


2.57 


2.26 


2.02 


6 

5 


3-5o 
4.20 


2.92 
3-39 


2.52 
2.86 


2.23 

2.48 


4 


5.25 


4-05 


3-30 


2.79 


3 
2 


7.00 
10.50 


5-00 
6-53 


3-89 
4.76 


3-20 

3-76 


1 


21 .00 


9-43 


6.10 


4-54 



* Coxe, Proc. N. E. Cotton Manufacturers' Assoc, 1895, 



TABLE IX. 

COMPARISON OF METRIC AND ENGLISH SYSTEMS, 

I cubic inch = 16.39 c - c - 

1 cubic foot = 28.315 liters. 

I Imperial gallon = 4.543 " 



I lb. avoirdupois = 453.593 grams. 

1 calorie = 3-969 B.T.U. (Rontgen). 



INDEX 



PAGE 



Acid hydrochloric, reagent 34 

Air-pumps, Bunsen's . 7 

, Richards' 7 

, steam o. 

Anthracite coal, analysis of , 45 

Aqueous vapor, table of tension of 79 

, specific heat 29 

Aspirator 9 

, Muencke's 38 

Bagasse calorific power 47 

Benzophenon, boiling-point 25 

Berthier's method of determining calorific power of coal.- ... 68 

Bituminous coal, analysis of 44 

, varieties 43 

Blast-furnace gas, analysis of 48 

Boiling-point of various substances 25 

Brown coal 43 

, analysis of 43 

Bunte's gas apparatus 16 

Calculations 27 

Calorimeters of Barrus 56 

Fischer 56 

Hempel 57 

Mahler 57 

Thompson, L 56 

Thomson, W 56 

Carbon dioxide, determination of 13, 18, 21 

, specific heat , 29 

85 



86 INDEX. 



PAGE 

Carbonic oxide, determination of 14, 19, 22 

, loss due to formation of 32 

, specific heat 29 

Charcoal, analysis of 45 

, preparation 45 

Coal, air required for combustion 45 

, calorific power ^ 45 

, formation of 42 

, method of analysis 50 

Coal-gas, analysis of 49 

, calorific power 49 

Coke, analysis of 46 

, determination of 50 

, preparation ; 46 

Cooling correction in calorimetry 67 

Course in gas analysis 39 

Cuprous chloride acid, reagent „. 34 

, ammoniacal, reagent 35 

Elliott's gas apparatus> 20 

Formulae, Bunte's, for calorific power of coal 69 

, Dulong's, for calorific power of coal 69 

, Lunge's, for heat passing up chimney 32 

, for heat of combustion with Mahler bomb 66 

, Mahler's, for calorific power of coal 69 

, Ratio of air used to that theoretically necessary.. . 31 

Fuel, determination of calorific power 56, 70 

, loss due to unconsumed 33 

Fuels, method of analysis of: ash 55 

carbon 51 

coke and volatile matter 50 

hydrogen 51 

moisture 50 

nitrogen 55 

oxygen 56 

sulphur 55 

Gas calorimeter, Junker's 70 

, determination of calorific power by calculation 74 



INDEX. 87 

PAGE 

Gas laboratory, arrangement of. 37 

Generator gas, see Producer-gas. 

Hydrocarbons, determination of 14, 23 

Illuminating gas, manufacture 49 

, Boston, analysis of 75 

, calorific power (calculated) 78 

Iron tubes, action of uncooled gases upon 2 

Junker's gas calorimeter 70 

Laboratory, arrangement of. . 37 

Lead, quantity reduced, a measure of the calorific power. ... 68 

Lignite 43 

Lunge's method for determining quantity of heat passing up 

chimney 31 

Mahler bomb 57 

Melting-point boxes 26 

Melting-point of various substances 81 

Moisture in coal, determination of 50 

Naphthalene, boiling-point 25 

, calorific power 65 

Natural gas, analysis of 48 

, calorific power 49 

Nitrogen, determination of, in coal 55 

, gases 14 

, specific heat 29 

Orsat's gas apparatus n 

Oxygen, determination of, in coal 56 

, gases 14, 19, 22 

, specific heat 29 

Peat, analysis of 4! 

, calorific power 42 

, formation 4! 

, moisture in 41 

Petroleum, formation of 47 



88 INDEX. 



Petroleum, crude, analysis of 47 

, calorific power 47 

Potassium hydrate, reagent 36 

pyrogallate, reagent 36 

" Pounds of air per pound of coal " 27 

Producer gas, analysis of 48 

, calorific power 49 

Pyrometer, Le Chatelier's thermoelectric , 25 

Quantity of heat passing up chimney 28, 31 

Ratio of air used to that theoretically necessary 31 

Sampling apparatus 3, 6 

gases, method of • 2 

, tubes for 2 

solid fuels, method of 50 

Semi-bituminous coal, analysis of , 44 

Sodium hydrate, reagent 36 

pyrogallate, reagent 37 

Specific heat of various gases 29 

Spent tan-bark, calorific power 46 

Sulphur, boiling-point 25 

Table of quantity of air necessary to burn gases 80 

tension of aqueous vapor 79 

weight of aqueous vapor in air 79 

calorific power of gases 81 

solubility of gases 82 

specific gravity of gases 81 

volumetric specific heats of gases 79 

weights of gases 81 

melting-points of metals and salts 82 

metric and English systems 83 

theoretical quantity of air supplied 83 

Temperature measurement of 24 

Thermometers 24 

, testing of 25 

Tubes for sampling 2 

Volatile matter, determination of , 50 



INDEX. 89 



PAGE 



Water-gas, analysis of 48 

, calorific power 49 

Wheat straw, calorific power 46 

Wood, analysis of 41 

, calorific power 41 

9 moisture in . 40 



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